JH402 GEOGRAPHY BLOG! (:

2009-05-19T21:04:00.007+08:00

Well, Pei Xin asked this question in class one day: Have we ever thought about why physical geography is put under Integrated Sciences? I thought it would be interesting to summarise this blog with this question as well as some other facts and notes about what we have learnt. Of course, the stuff I put up here are just really brief summaries of what we learnt, so everyone better go and mug still!

I remember Mr Heah once said, physical geography is a science on itself. Earth science. Maybe that’s why it is put under IS? Physical geography studies more of the features on Earth. For example: volcanoes, atmosphere, hydrosphere, rivers etc. If you all paid close attention, actually within all these features/topics, science is very important. It’s all about how everything works in a system. Once you understand one part, and link it up with other parts, there you have it! Everything linked up together which makes perfect sense. I feel that science is more on how things work as well as why things work. How they happen, and why they happen. That’s mainly the reason why I think physical geography’s under IS.

Okay, now for the summaries.

So here's basically like the rough idea that we need to study according to Pei Xin.

HYDROSPHERE:

ATMOSPHERE:

ALL THE BEST PEOPLE FOR GEOGRAPHY!!

- joanne

2009-05-05T20:49:00.000+08:00

The geo test will be on week 10
The following topics will be tested:
Atmosphere:
Climographs
Seasons
Climates
Rain/clouds formation
Hydrosphere
Water cycle
Water balance
Hydrographs
Features-formation
do revise all these and jiayou for your test :)

xingru

River features: Waterfalls, meanders and braidings

2009-05-05T13:29:00.005+08:00

This post is about the content of two lessons which are on 28th of April and 29th of April.

Waterfall

(From: http://i1.treknature.com/photos/413/marokopa_falls2.jpg)

Definition: A waterfall is a sudden step in a river's long profile.
Reasons for its formation: The main reason for the formation of a water fall are different bands (layer) of rocks through the bed of a river. When a river is flowing on the ground, it will erode the rock band on its bed. If this erosion happens on the cross section of different layers of rocks, a difference in erosion will occur because of the different hardness of different kind of rock. Therefore, when the river flow through from a harder rock band to a softer rock band, a steep step will be formed because of the difference in erosion. This is how waterfalls are formed.(from: http://www.dkimages.com/discover/DKIMAGES/Discover/previews/774/206846.JPG)

Meader
Definition: Meaders are the wind and curve features through river's' course. Meaders are brobably the most common river feature.
Reasons for its formation: Meanders are formed mainly because of the riffles and pools in rivers. Riffles and pools are the shallower and deeper part of a river's bed. Water will never flow straight so that rivers will be twisted even if they are straight originally. When water flow through riffles and pools, a Helicoidal flow will occur because of the differences in velocity of river flow.

Helicoidal flow

(From: http://4.bp.blogspot.com/_HTS0iL2pEqg/SX9DGgXAThI/AAAAAAAAAC0/5yod3DhDdew/s320/helicoidal+flow+3.jpg)

Helicoidal flow is a cockscrew movement of water responsible for moving eroded river load from the outer bank and then depositing much of it on the next inner bank of a river. When helicoidal flow happens, river will start to shift outwards. This will make the river even more winded. Meanders will finally be formed by the during the process of helicoidal flow.

(From: http://1.bp.blogspot.com/_HTS0iL2pEqg/SX9B79oQmTI/AAAAAAAAACs/pHwithMStrE/s1600/helicoidal%2Bflow%2B2.bmp)

(From: http://www.ucpress.edu/books/pages/6664/moj01a.jpeg)

Braiding
Definition: Braidings are formed when a river subdivides into many smaller streams within its channel.
(From:http://www.braidedriver.net/braided_river_blue.jpg)
Reasons for its formation: There are two resons for the formation of braidings. One is the easily erodable channel sides and the other is the highly irregular discharges. Easily erodable channel sides make it easier for water to erode out different routes or gaps. And irregular discharges make it possible for water to have different velocity and baseflow. A different route of water flow may be formed when there is a change in velocity and base flow. This will make up some small island in the river. And this is how braidings are formed.
(From: http://www.gly.uga.edu/railsback/1121RiverOxBow.jpeg)
The picture above is the formation of a Ox-Bow Lake. It also reflected the effect of different discharge. In the third picture, a braiding is formed because of the larger discharge in that period.

Poster: JAY ZHAN WEI HENG

2009-04-23T01:15:00.012+08:00

I will be doing the blog posts on two lessons, last week’s (14th April) and today (22nd April).

Last week’s lesson was a rather short lesson. Basically, we learnt about a river, that a river has energy, and that various energies affect how a river behaves or looks like. Also, we discussed about the different factors that affects a river’s energy.

A river’s energy is mainly contributed by:
1. Volume
2. Velocity
The higher the volume and velocity of a river, the more energy a river has.

So what affects the velocity of a river? Basically, there are mainly two factors involved, namely Gravity and Friction, in other words, Channel Shape.

Moving on to today's lesson, we learnt about the different features and formations of rivers , about the Hjulstorm curve works and how velocity is a vital component in determining how a river behaves.

Firstly,
What are the different sections of a river?

What is Erosion?
Erosion is defined as the picking up and removal of material.
There are mainly five processes affecting erosion:
1. Corrosion
2. Abrasion
3. Hydraulic action
4. Solution
5. Attrition

Hjulstrom Curve

Area between erosion and deposition velocity: transportation of load occurs
Area above erosion velocity: erosion of load will occur
Area below deposition (fall) velocity: deposition of load occurs

Note: erosion and deposition velocity values vary with load!

Ok then, i’m done
Darryl
P.S. I apologize for the low quality pictures

8th April 2009

2009-04-09T22:26:00.021+08:00

Today we revisited the factors which affected the hydrographs as well as went through the answers for the exercise given to us(pg 231 of text). We also learnt more about various factors such as shape of basin and how it affected the hydrographs and more about drainage density.

This is mainly what we went through for the answers in the activity:

1. Lag time
2. Shapes of basin affecting shape of hydrograph
3. Drainage density and how it affects hydrographs
4. Effects of vegetation and urbanization on hydrographs

So what is a drainage basin? For those who did not know yet, it’s actually like the idea of funnels, the imaginary area where rainwater collects or drains into.

Firstly, Lag time.

“Lag time” is defined as the time between peak rainfall and peak discharge. Another explanation could be the time taken for the river to react to rainfall.

Lag time happens because of processes like interception, stem flow, infiltration as well as percolation which affect the movement of water (see picture below).Therefore, the water will take time to flow and reach the mouth of the drainage basin, going through other processes such as base flow to reach the drainage basin.

(Baseflow – defined as the basic amount of water flowing through the river when there is no rainfall.)

Link between lag time and likelihood of flooding:

With a shorter lag time, the more the runoff, if the water level is higher than bankful discharge, it would mean that flooding will occur.

For example, look at these 2 rivers. Note that the amount of rainfall is the same.

River A (Shorter lag time)

There is a lot of runoff(overland flow) in river A, thus causing the water level to raise above bankful discharge.

River B (Longer lag time)

In river B, factors such as bigger surface area, increase in interception, infiltration and percolation, thus the water will take a longer time to flow. With a longer time to flow, there is lesser runoff, thus the amount of water does not exceed it’s bankful discharge.

(Bankful discharge: Maximum amount of water that can flow in a river without over flowing it’s banks)

Secondly, we discussed about the shape of the basins and how the shape affected the shape of the hydrograph (pg 230)

Drainage basin C Vs Drainage basin D ( long vs round drainage basin)

Drainage basin C

Drainage basin D

Graph Between drainage basin C and D

After a certain amount of period of time, ( ie. 1h, 2h, 3h) the amount of water collected from each basin is different. For river D, over a longer time, the amount of water collected increases as for river C, the amount of water if fairly constant with little change.

We also discussed how different shapes affected the graphs, how much water and how long the water will take to reach the mouth of the basin.

[The numbers represent the water flow, and 1 comes first as it is nearer to the mouth of the drainage basin. The arrows show the different distances the water has to flow before reaching the mouth of the basin and how much water there is, thus affecting the shape of the graphs.]

Thirdly, drainage density.

The higher the drainage density, the more rivers, which would mean more surface runoff (When water falls as rain, it directly falls into the rivers, going straight to the mouth of the drainage basin.)

Drainage Basin A (Lower drainage density)

- Graph tends to be gentler

Drainage Basin B (Higher drainage density)

- Graph tends to be steeper

Lastly, moving on to the effects of vegetation and urbanization.

- Vegetation -> increase in interception -> increase of infiltration -> increase of ground water. Therefore longer lag time, less steep rising and falling limb of hydrograph.

- Urbanisation -> decrease of infiltration -> increase of runoff -> decrease of ground water. Therefore shorter lag time, steeper rising and falling limb of hydrograph.

Yup, That’s all folks!

Darren.

April 7th entry

2009-04-09T15:37:00.001+08:00

Today Mr Faizhal went to our class and told everyone to read the textbook page 240, which is about the River channel processes. Here is a summary of these 2 pages:
Water energy depends on: the amount of water
the steepness of the slope.
Competence: ability of river to transport sediment.
Load: material carried by the river.

Sediment movement depends on:
1) Nature of the bed and banks
2) The flow of the river
3) Human intervention.

Erosion: the picking up and removal of material. Three processes of erosion:
1) Corrasion (most significant type): particles of rock carried by the river grind away at the bank and bed.
2) Hydraulic action: water crashes on onto the bed or against the banks.
3) Solution: Carbon dioxide in water may react with limestone and chalk.

Deposition occurs where particles can not be carried any more due to the small flow speed. Some places where it can occur: inside bend of meander, bed of river, close to river’s bank, where river enters the sea, etc.
Velocity is the main factor controlling transportation, erosion and deposition.
The Hjulstrom curve has a critical erosion velocity line and a critical deposition line. Basically, it is like this:
- The larger the particle the greater the velocity required to pick it up. (It makes sense right)
- However the small particles tend to stick together, so higher velocity required to pick them up. (It also make sense right?)
- Velocity falls, successively smaller particles drops.

There is an increase in velocity with distance downstream, due to:
- Greater volume of water, because water from many sources join the main flow.
- Roughness of channels is reduced because silt replaces pebbles and boulders è less turbulence.
- Channel tends to adopt more efficient profile.

It was raining romantically today, that’s why Mr. Faizhal asked the whole class to go out and look at the rain. We observe the overland flow, the process of interception and the maximum infiltration capacity of the land. We observe the flow of water outside 01 classroom. We discussed the hydrograph of a random point along the flow. The hydrograph should be very steep with a short lag time.
That’s all we have for today lesson. It was quite interesting as the whole back row people were laughing all the times, and no one slept in class.

-Lam-

1st April 2009

2009-04-06T09:42:00.002+08:00

Hi all! Happy April Fool's Day! Sorry for the belated post for the 1st of April Geography Lesson with Mr. Faizal. Anyway, here it is:

We started of on the revision of water balance, where Input = Output. Input consists of the precipitation and the Output consists of total streamflow (Q), evapotranspiration (E) and storage (S).

We then moved on to the section on Hydrographs. Basically, a hydrograph shows how a river reacts to rainfall. So there are 5 main sectors of the Hydrograph.
1) Antecedent flow rate
- This is the point before the rainfall effect starts and is at the start of the hydrograph
2) Rising Limb
3) Peak of the graph
- This part of the graph is known as the peak flow rate, where peak discharge is observed
4) Falling Limb
5) Groundwater recession
- After the rainfall, when the river's discharge is close to zero.

And there are other important details to remember in a hydrograph.

Firstly, the baseflow and stormflow. The storm flow is the sector of the graph between the rising limb and the falling limb and the baseflow is the sector of the graph between the Antecedent flow rate and Groundwater Recession.

Secondly, the bankfull discharge. The point of bankfull discharge is determined by calculations. If the graph goes above the bankfull discharge level, it means that the river experiences a flood.

And thirdly, the lag time. Basically, the lag time is the time between peak rainfall (Antecedent flow rate area) and peak discharge (Peak flow rate of graph)

We then evaluated how and why storm hydrographs differ. This is dependant on many factors, such as the rate of rainfall, amount of rainfall, and basins with impermeable bedrock.

The rate of rainfall determines the overland flow. If there is high rate of rainfall, there is high overland flow, resulting in dramatic hydrographs, with steep limbs and high peaks.

Less dramatic hydrographs occur when there is light, summer rain when evaporation rates are high and when discharge is easily absorbed.

Ok, so that's about it! I hope I didn't miss out much. Please add in comments too. See Ya!

Akshay

WATER BALANCE

2009-03-31T22:51:00.004+08:00

The first thing which is also the only thing, we learnt today, is WATER BALANCE. A water balance can be used to help manage water supply and predict where there may be water shortages. It is also used in irrigation, flood control and pollution control. All we need to remember is just an equation: P= Q + E + △S (Input= Output). P is precipitation. Q is total streamflow (runoff). E is evapotranspiration. △S is the change in storage (in soil and bed rock).

When △S = 0, what will happen?
-The soil cannot absorb water any more
- This kind of soil cannot attract more water.
- Using the wrong kind of soil.
All in all, there is no soil storage.

Here are several cases that can influence water balance.

That’s all for today’s lesson. Although it is very short, it is quite important for us to have a better understanding on water cycle.

Done by Tianyu

25 March 2009 Geog Blog Post

2009-03-25T21:59:00.003+08:00

We talked about the drainage basin and how it helped...um...drain water and stuff like that. We also talked about how to locate and find the start and end of the drainage basin. How different types of soil have different types of storage capacity, known as infiltration capacity. Which is the amount of water the soil can hold before overflowing. Now for water, the most important thing about water and the most unique is the fact that it is bonded by hydrogen bonds. Water has a very very VERY wide temperature range, this means that remains in liquid form over a wide range of temperatures.
brendan

Introduction to Hydrosphere

2009-03-24T17:04:00.004+08:00

Hey all.
Today we had lesson on Hydrosphere at the beautiful garden.

If all of you recalled, we already touched on hydrosphere last time - the basic water cycle. Water evaporates from water bodies, rises, expands and cools (adibetic cooling). Then the cloud gets heavy and water droplets fall from the sky as raindrops.

Water is ESSENTIAL for life. Some micro-organism can survive without atmosphere but NOT water. During seasons change, life forms are also affected due to the water available. For example, during winter and autumn , plants start to wilt due to the scarcity of water. During spring and summer, life flourish. Not just seasons, the place also affects the amount of water available. For example, at the tropical countries where it is wet and warm, forests are very densed. At deserts, there are very little plants due to the scarcity of water.

To understand the drainage system- imagine yourself as a cute little water droplet. What will happen to you?

Fall onto the soil, seep into the soil and join the ground water (infiltration). Infiltration capacity is defined as the amount of water the soil can hold.
Flow laterally downslope (throughflow)
Flow laterally horizontally (baseflow)
Get intercepted by trees and leaves (interception). Tree by itself acts like an inverted drainage system.

Changing the ground from soil to concrete can change the entire system of drainage. This changes the amount of groundwater available and the amount of water available in soil thus affecting the availability of water for plants and affecting the whole bio system.

Now, isn't that interesting and amazing? Thank you!

JH.

Summary Of Atmosphere

2009-03-24T12:11:00.002+08:00

Hello Everyone! This will be the Summary of the first half of our Physical Geography Module, IS2104. We have learnt a lot about The Atmosphere of our Earth throughout the entire Term 1.

Well, the Atmosphere's structure can be split into 4 sections - Troposphere, Stratosphere, Meosphere and Thermosphere. The Troposhere distributes heat energy throughout the Earth, while the Stratosphere contains the Ozone Layer. The Atmosphere is composed of 21% Oxygen, 78% Nitrogen and 1% Other Gases. Carbon dioxide (<>. The Greenhouse Effect traps heat from the sun in the atmosphere and also helps reflect infared radiation.

Progressing on, we learnt about the Planetary Heat Balance, which is a system that helps to keep Earth in thermodynamic equilibrium. 100 Units of heat energy from the sun enters the Earth. 19 units of insolation are absorbed in the atmosphere(17 by Clouds And Aerosols; 2 By Ozone), 23 units are scattered and subsequenly absorbed by the Earth's surface as diffused insolation, 28 units are absorbed by the surface as direct insolation, and hence the total number of units of heat energy absorbed by both the Earth's surface and atmosphere is 70 units. However, much of this shortwave solar radiation is also lost back to space. 4 units return via surface reflection, 20 units via cloud reflection, and 6 units via back scattering of sunlight, bringing the total loss of shortwave radiation to 30 units.

Longwave radiation also leaves the Earth. 7 units via sensible heat and 23 units via latent heat transfer. Earth's surface also emmits 117 units of longwave radiation, of which 6 are directly lost to space, and 111 units are trapped by greenhouse gases. (NOTE: This is Where Humans are changing the Atmosphere's composition and subsequently causing Global Warming) The Earth's atmosphere emmits 160 units of longwave energy, which comprise 111 units of surface emissions of longwave radiation, 23 units from latent heat transfer, 7 units from sensible heat transfer, and 19 units from the absorption of shortwave radiation by atmospheric gases and clouds. 64 units of atmospheric emissions is lost directly to space, while 96 units travel to the Earth where it is absorbed and transferred into heat energy.

Moving on, we studied rain - types and formation. Adiabatic cooling occurs when air rises, expands and cools. Relief Rain is formed when adiabatic cooling occurs near relief. Air is forced to go over the elevation, it cools, expands, rises and thus results in rain forming on the windward side of the elevtation. Frontal Rain occurs when a warm air mass and cold air mass collide. Warm air comes from the equatorial regions, while cold air comes from the polar regions. When the two air masses collide, warm air is forced to rise, Adiabatic cooling occurs, thus clouds form and rain results. Such rain is found at temperate regions, where cold air and warm air meet. Convectional Rain occurs when warm air rises. The Earth's surface heats up, as it absorbs heat energy from the sun, and the surface of the Earth transfers heat to the air via conduction. When the warm air rises, adiabatic cooling takes place and clouds from, causing convectional rain. Such rain is found at tropical regions, beause it is sufficently warm, and it occurs usually in the afternoon and evening.

Climate basically refers to how warm and wet a particular location is, over a period of time. The former is measured in terms of temperature, and the latter in terms of precipitation. We can use Climographs to describe climate patterns of different locations. The Earth's climate is not uniform throughout, and varies all around. Essentially, the Earth's tilt and shape result in the distribution of Earth's climate. Climates are distributed among lattitudes. It is warm at the equator, and gets cooler as you progress along the lattitudes, towards the poles. At the equator, the sun's radiation is spread over a small area and is hence very intense, resulting in equatorial regions being very warm. Moving away from the equator, the sun's radiation is spread over increasingly large areas and is thus less and less intense, resulting in temperatures turning lower and lower.

The seasons of the Earth are caused by the changing orientation of the hemisphere with regard to the sun, when the Earth revolves around the sun. The Earth is tilted at an angle of 23.5 Degrees, and during 6 months of the year, one hemisphere receives more sunlight than the other. During Solstices, the particular hemisphere receiving more sunlight will officially begin summer, while the other hemisphere will begin winter. During Equinoxes, both hemispheres will have equal amount of sunlight. Equinoxes indicate the time whereby one hemisphere will begin receving more sunlight, and the other, less.

Finally, Mr Heah also taught us about the Global Air Circulation. The Earth can be split into the Polar Cell, Ferrel Cell and Hadley Cell. Warm air from the equator rises and eventually sinks at the polar regions. This would be the Hadley Cell. At the Polar region, air also rises, and this would be the Polar Cell. A third cell exists in between both, and is known as the Ferrel Cell. Almost no air rises from the Ferrel Cell, and there is thus very little precipitation there. Since this is so, there are few clouds above the Ferrel Cell, resulting in unstable and unregulated temepratures that vary drastically with the time of the day A.K.A DESERTS. A final point to note would be that due to Earth rotating from east to west, the pathway of air will swing westwards.

Thank You and I hope this has been beneficial.

Andrew

Last Night's Rain

2009-03-06T21:57:00.004+08:00

Hello 02. Today in class, Mr Heah posed a very thought-provoking and intriguing question - where did last night's torrential rains come from? We discussed the answer in class, and it is as follows.

The rain was essentially monsoonal rains, coming from the South China Sea.

Since the thermal equator was at the Tropic of Capricorn just last december 21st (Winter Solstice), the Southern Hemisphere, as compared to the Northern Hemisphere, has been receiving more intense heat these past months from December till today in March. As such, the surface air of the Southern Hemisphere is warmer, expands more, and the Southern Hemisphere hence has a lower air pressure. Thus the colder, denser air of the Northern Hemisphere is moving southwards, and going by the direction of wind flow as shown in the Hadley cell, the air will flow in the south-west direction. Thus, as the wind travels over the South China Sea, it picks up moisture, and when the moisture-laden rain passes Singapore, it results in monsoonal rains occuring in Singapore last night!

andrew

Geography lesson, 2nd March 2009

2009-03-02T20:42:00.007+08:00

Today, we have started a new topic in atmosphere which is the Global Air Circulation. Basically, we have learnt how air circulate around Earth. And thus we know why desserts are not formed around the equater.

Today's lesson Mr Heah introduced us a way to make our own simple model of air circulation. Firstly, we need to remove all possible variables to be able to see how only one factor affects the other. So, we romoved all the factors but HEAT from the sun. Because of the uneven distributed heat energy from the sun, for the equator part heat energy is distributed the most intensely part, thus it is the hottest. But for the poles, because energy is distributed to a largest surface area, it is the most diffused around there. And because atmosphere is liquid, convection current will be set up. Therefore, hot air will rise from equator and sink down at the poles. This model is called single cell model which has been blamed for too simplistic.

Then, Mr Heah introduced us another model called three cell model. Basically, in this model, air rise from the equator, and cold air will still sink at the poles. But, along the way that air is travelling, they will sink as well. This convection cell is called Hadley Cell. And around some where near the poles, there will be air rise as well. This cell is then called Polar cell. Then, in between those two cells, there is one more convection current cell, Ferrel cell.

And based on this diagram, we can see why desserts are always formed around from somewhere above equator. As you all can see from the diagram, for the Ferrel cell, the air rises from the terminal which is nearer to the pole and sinks at somewhere above equator. And for Hadley Cell, the air also sinks at the point that air sinks for Ferrel Cell. Thus, there is almost no air rises from that place. Furthermore, because rain is formed when hot air rises(water evaporate) and water vapor condenses then to form clouds and rainfalls. However, for that area, air won't rise, thus there would be very little percipitation here. Thus, desserts are always formed here. Whereas, although, equator recieve the most intensive heat from the sun, but because there are a lot of water evaporate as well, hence, this place recieve quite amount of precipitation every year. Also, we have talked about the cause of charatistics of dessert using air circulation to exphenlain. Because there will only be clouds formed if there is water evaporate from the grand, there will be no or little clouds in the sky. And the clouds can help reflect or keep the heat from the sun, so they can help regulate heat and temperature of a place. Therefore, in dessert, during day time, the temperature is very high whereas at night the temperature is very low.

After finding this three cell model to discribe the air circulation, we added in another affecting factor, the rotation of earth itself. Then, there is another more complicated model.

Because earth will rotate from east to west, the pathway for air flow will swing to the west a bit due to inertia.

From this lesson, the most important thing that I have learnt is how to solve a complicated question. It is just like how to generate the model for air circulation. First of all, we need to break down all the affecting factors and then concentrated on one factor. Then, after that, we should continue to add in other parts to make the model(answer) complete. Also, one more thing to notice is that when we are solving other confusing problems, we should take the easier one to do first and keep adding other harder parts to perfect your answer.

Wen Yu

2009-02-28T18:20:00.003+08:00

Geography lesson, 27th February 2009

Today, our Geography lesson is quite exciting.
Once again, Mr. Heah told us about the better way to study geography. As you all know by now, memorizing is strongly discouraged. But the very fact is that you will still need to sit for exams. So Mr.Heah said the most effective way is to study using your logical/critical thinking (study the Earth as a system) to generate your own knowledge.
After that, we came back to answer the two questions brought by Mr.Heah last lesson
1/Explain the distribution of Earth’s climate
Once again, splitting up the questions to get the main ideas is important. There are several questions you need to think about before you can attempt to find the answer for the main question (as mentioned by Sue-ann in the last post).
However, the most fundamental question you need to think about is what is the Earth’s climate distribution. And I do think that the more important thing is to find out the “how” behind the “what”.
If you look at the World Map of Koppen-Geiger Climate Classification given, you should notice that there is a banding pattern in the climate distribution. This banding pattern is actually along the altitude and is symmetrical along the equator. So, there are some more questions we need to think about before we can reach the final answer.
1. Why is climate different in different regions of the world ( polar, temperate, tropical, temperate, polar )
2. Why is the climate distribution patterned the way it is?
My group came out with several single words to answer those questions such as radiation, heat, shape, tilt, etc. However, we then look at specific features of each type of climate over certain regions. The climate is actually identified to be warmer at equator and cooler as approaching to polar regions. Does it have any link to radiation energy from the Sun? We know that the intensity of radiation has nothing to do with the distance from the Sun to certain region that receives the energy. However, over larger distance, the energy will be diffused and by the time it reaches the surface, it will be less intensive. Here, looking back at our Earth, the equatorial region receives the most intensive radiation from the Sun. Thus, this region is always warmer compared to the polar regions which are farer from the Sun ( by the time radiation reaches those regions, it is less intensive as it has been diffused over space ). Once again, we need to think. Why is it so, why does equatorial region receives most intense radiation from the Sun while polar regions are farer from the Sun, thus get less intense radiation? It is so simple that the answer can be expressed in only one word. It is because of our Earth’s SHAPE. (circular)
So all in all, the answer to a the question actually lies in one key word : SHAPE
2/Why are there seasons?
What are seasons in the very first place?
The most important thing we should know about season is the change of weather (ex, from low to high temperature and vice versa)
Here, we need to look at the climographs given, it is notable that the change occurs in the middle of the year.
Some may ask are the seasons results of changes in the distance from the Earth to the Sun? No, they are actually not.
In our lesson today, we learn that our Earth spins on a tilted axis (this axis is an invisible axis through the center of the Earth) once every 24 hour. That’s why there are day and night.
In addition, the Earth revolves around the Sun once every 365.25 days. As such, the tilt of the Earth causes different regions of the earth to point towards the sun (over specific periods of time). This causes different amounts of sunlight to reach the same surface area of the Earth throughout the year. The different amounts of sunlight lead to different weather at this location
There are seasons because the Earth’s axis of rotation is tilted 23 degrees. In June, northern hemisphere is tilted towards the Sun, so the sunlight has the more direct path to the Earth surface, thus, there are more hours of sunlight during the day. As a result, it is summer in northern hemisphere. Meanwhile, in southern hemisphere, the sunlight has to go a longer path to the surface and the days are shorter in June. So, it is winter in southern hemisphere.
So, basically, looking back at the question and the detailed answer I have written, the main point lies in the word “tilt”
All in all, answers for many questions can be expressed in one word or few. The important thing is that you need to use those few words to generate your own complete answer from what you already know. This is a better way of learning.

So that's about it :)

Chi

2009-02-23T21:23:00.002+08:00

Today we had a short lesson. We learnt a lot but very little. A lot of concepts and ideas and theories, but very little put in words. This is something I think we need to brush up on. How to express our answers in words.

So, the first question posed to us was:

Explain the distribution of the Earth's climate.

Splitting the question up, we look at the words distribution and Earth's climate respectively.

What is distribution?
Which areas?
Why?

What is climate?
How many types/kinds of climate?
What is the difference (how to tell them apart?) ?

From what we have learnt so far, we are already able to answer question 1. What is climate? It is how warm and how wet a particular place is.

We were then splitted into groups according to our birthdates! Interesting way of grouping. Some of us were to answer the question above, and others were to answer the question below.

Why are there seasons?

For my group, we came to understand that seasons are caused by the 23.5 degrees tilt of the Earth on its own axis, AND the revolution about the Sun. The amount of insolation the Northern hemisphere receives from the Sun determines the seasons it is going through.

During the period of June, the incoming solar energy is the greatest in the Northern Hemisphere, thus it is going through summer. Looking at your notes, Figure 2-11, the diagram shown is a clear representation of the tilt towards the sun in June. It is clear that the Northern hemisphere receives most insolation from the Sun then. Vice versa for the winter time in Dec for Northern Hemishpere.

As the year goes by, the rotation of the Earth on it's own axis plus the revolution around the Sun causes Autumn , Winter, Spring to follow as well.

When Spring and Autumn is in place, the position of the Earth towards the Sun allows equal amounts of insolation for BOTH hemispheres. though the position of the Earth during Spring and Autumn receives same amount of insolation, it is different because when Summer becomes Winter, (warm to cold) leaves dry up start to fall: Autumn. When winter becomes summer (cold to warm) leaves are given more warmth and all life needs warmth to grow therefore Spring comes.

So far this is what we have concluded. Coreect me if i'm wrong and, if your group is ready to share your view on any of the 2 questions, please comment. *winks*

Sue-Ann. [:

Climographs

2009-02-20T18:16:00.022+08:00

We revisited climate and precipitation over again today. There’re just a few main points that we need to remember, in order to describe climographs accurately and concisely, so here it goes.

Climate: Tropical (Arid), warm or cold temperate, polar (tundra)

To differentiate warm or cold temperate countries, warm temperate countries have warmer winters and summers whereas cold temperate countries have cooler summers and winters.

When describing climate, we need to say:
a) How warm it is–
This is measured in terms of temperature (not a description). Humidity is NOT included.
BE SPECIFIC: Is it freezing cold, cold, cool, warm, or sweltering hot?
After we focus on magnitude, focus on the distribution throughout the year (compare to seasons). Is it high, low or moderate? Then, we focus on the range. Is it small or large?
b) How wet it is—
This is mentioned in terms of how much liquid is precipitated. We use the term precipitation as it includes snow, hail, etc, whereas rainfall does not. Move on to describe precipitation; is it dry(draught season), or wet(monsoon)? Is it even, or uneven?

Then, we can see if there is a pattern between precipitation and rainfall. In countries such as Tokyo, temperatures and precipitation increase at decrease at around the same periods. If there is none, then nevermind.

Additional point: To describe temperature or precipitation, we put anomalies aside in order to determine the precipitation kind or temperature type. Always remember that climate is based on how wet, and how warm a country is.
My opinion: I think a good climograph description should be able to reflect the temperature and precipitation in a country in someone’s head if there is no climograph.

Barrow, Alaska, USA
- Generally freezing cold and dry.
- Extremely low rainfall, with peak periods of July to October at 20mm. Mostly, rainfall during the year barely reaches 10mm.
- Temperatures are usually sub zero (below zero) with warmer months from June to September at 1°C to 5 °C, and cold months occur in December to February at around 28°C.
- Warmer and wetter periods exist from July to October, whereas Colder and drier periods from December to February.
- Climate is typical of a Polar tundra.

Santiago, Chile
- Santiago has a warm temperature climate throughout the year. The temperature has a large range from 8°C to 20°C. The highest temperature is 20°C in December to February, followed by a steady decrease in temperature to a low of 8°C. After this decrease, temperature steadily rises back to 20°C.
- Santiago receives an uneven amount of precipitation throughout the year. It is dry during summer and slightly wet in winter, autumn. The range is from 0mm to 9mm. This precipitation differs from the temperature graph in a way that when temperature is high, rainfall is of a minimal amount. Conversely when temperature is low, rainfall is rather high. It increases to 9mm in June, followed by a decrease to 0mm in December, which lasts till about March.
- Climate is typical of a hot, arid one.

Bombay, India
- Bombay is HOT, and has a fairly high temperature which is constant throughout the year with monthly average temperature between 23°C and 30°C.
- Bombay has a very uneven distribution of precipitation. During its wet season between June to September, it receives an intensive precipitation, especially in the month of July. (Approximately 650mm.
NOTE: In some countries, temperatures rise, as well as rainfall. However, this is just a trend, not that it is supposed to be that way.
- In September, there is a sharp drop in precipitation, followed by the rest of the months in the year (November to March), in which it is extremely dry and receive on average a precipitation below 10mm. This is very low, and sometimes so low that it hardly receives any rainfall.
- This climograph is typical of a tropical monsoon climate.

Tombouctou, Mali
- Tombouctou, Mali has a warm climate with temperatures ranging from 20°C to 33°C throughout the year. Temperatures increase steadily towards midyear (Jan) from 20°C to 33°C in June, and decreases from mid year to year end (Dec) from 33°C to 20°c.
- Tombouctou, Mali has a dry climate with rainfall less than 50mm for most of the year except during the mid year (June to Sept) when it gets slightly wetter with precipitation of approx 80mm.
- This climograph is of a tropical, arid climate.

London, England
- While temperatures in London tend to rise and decrease in the year, rainfall tends to remain around the same amount.
- London has a cool climate with a steady increase in temperature from Jan to july (approx 5°C to 18°C). When temperature reaches its peak in July, it starts decreasing to a temperature of 5°C from July to December.
- London has a relatively even distribution of precipitation throughout the four seasons (approx 50 to 70mm.)
OR
- You could say: London has a rather small range of precipitation throughout the year.
- This climograph is of a typical warm temperate climate. (warmer summer and winter).

Tokyo, Japan
- Japan has a relatively cool climate throughout the year. From Jan to Aug, there is a steady increase of temperature of approximately 4°C to 26°C. Temperatures reach their peak at around August, followed by a stable decrease to approximately 6°C.
- Japan is relatively wet—its precipitation mostly averages from 100mm to 200mm. It is rather high in the months of June, September and October, but precipitation is fairly low from November to February comparatively. In months such as July and August, precipitation drops from June, then rises in September, where it is supposedly supposed to increase in relation to the steady upward trend. The precipitation graph tends to follow the temperature graph.
- This climograph is typical of a warm temperate climate.

Brueno Aires, Arg
- Brueno Aires has a moderately high range of temperature varying from 9°C to 23°C. The hottest months are from Dec to March where temperatures hit above 20°C. This is followed by a decrease in temperature in the months of march to August, in which temperatures are lowest in June. Subsequently, temperatures then resume with an increase.
- There is a relatively even amount of precipitation throughout the year, of less than 100mm. Dry months exist in the months of May to August of approximately 50mm, and in September to April, precipitation is of a larger amount. The peak is during March, reaching a high of 110mm.
- Brueno Aires has a fairly wet climate.
- This climograph is typical of a warm temperate climate.

McMurdo Station
- Fairly constant and low precipitation throughout the year, ranging from 0mm to 10mm. The climate is extremely dry, with sub zero temperatures ranging from approximately -26°C to -4°C. In the months of April to September, temperatures are extremely low as it is during the cold seasons (approx -22°C to -27°C) with moderately constant levels.
- From Jan to April, there is a steep and steady decrease in temperatures of -3°C to 22°C, as it is the transition between Summer and Winter.
- Comparatively, there is also an increase in temperature from September to December, marking the progression between winter and summer.
- This cold and dry climate is typical of a polar tundra climate.

Yakutsk, Russia
- Cool summers and freezing cold temperatures during winters, rather dry all year round.
- Temperature fluctuates greatly, with drastic increases and decreases (large range of temperature/ huge temperature differences at different times of the year.)
- Winter temperatures of -40°C or even slightly below. Summer temperatures are approx 15°C to 20°C.
- As temperature increases, precipitation generally increases.
- Generally, very low precipitations with peaks at 50mm in July, (summer) and with very low levels of precipitation during winter months.
- This climograph is typical of a polar tundra climate.

Yea. That's about it. yunwei

2009-02-16T21:12:00.006+08:00

CLIMATE GRAPHS.
Today’s lesson was rather short and sweet. (:

Basically, to determine :
1. how warm a climate is, we look at the temperature
2. how wet a climate is, we look at the amount of precipitation.

When reading climographs, we convert the amount of precipitation into mm. Note: (1cm=10mm)
There are 3 axis for climate graphs, and JFMAMJJASOND stands for the months in a year.

The line graph tells you the average monthly temperature,
and the bar represents the average monthly precipitation.

Things to note:
1. Always look at the title
2. Look at the temperature and amount of precipitation
MOST IMPORTANTLY: ALWAYS TAKE NOTE OF THE UNITS

Usually what you will be asked to do is to:
1. Describe how warm or how wet a place is.
2. Read temperature and precipitation, and describe what you see.
3. Describe the general pattern(magnitude)
4. Look out for the anomalies
5. What kind of climate does this country have? (Polar/Tropical/Temperate)

Example. Singapore's climate would be tropical, as it is warm and wet.
If countries are less wet than Singapore, we can describe them as mildly wet.
In addition, for countries such as Bombay, their climate would be described
described as very wet due to intense rainfall.

Thats all for now. (:

Cheers!
-grace :D

official rainmaker

2009-02-13T22:55:00.010+08:00

Well, friday's lesson started with the question, “What do you remember about the water cycle from primary school? (throughout this blog post, ill mainly be focusing on the red box).

Then we went on to the “cloud in a bottle” experiment and what we observed is that only after adding in the smoke, when the bottle is squeezed, we don't see “clouds” however when we release it we see “clouds.” Yes, you guessed it, its all related to pressure and this is very much like how clouds are formed. But what is the link between pressure, smoke and clouds?

Well, since clouds do not appear in our homes, we can safely say that yes, pressure on earth is higher than that in our atmosphere. Lets say you have 100 units of heat for an ice cube(solid state). Now if I want to make this solid a liquid, I would have to force these molecules apart, as in the liquid state, molecules are further away from each other, this would eventually leave me with less units of heat as the molecules have absorbed the heat energy to move apart. Now think, if I were to make this liquid into a gas, I would have to again force the molecules apart, this time further than before and I am thus left with even less units of heat.

What does all this mean? Well, it is simply that releasing the pressure allows air to expand, and in doing so, the temperature of the air becomes cooler. Thus condensation occurs but clouds do not form because the water droplets are too small. So what happens? The water droplets collide instead of coalescing to form clouds. The air now is super saturated however, the water droplets would group together more easily if there are some solid particle in the air to act as a nucleus. This is where the smoke comes in, thus the cloud only forms when you add the smoke into the bottle. In the troposphere, the solid particles in the air may be in the form of pollution, smoke, dust or even tiny particles of dirt.

We now know how clouds are formed, but do you know how rain is formed? And did you know that there are 3 different types of rain? (well there may be more but we only covered 3 during lesson)

The three different kinds of rain are namely relief rain, frontal rain and convectional rain. Before I carry onto explain how each of these rain is formed I would like you to know what adiabatic cooling is. It is basically a process whereby air is forced to rise,expand and then condense to form water droplets.

Relief Rain:

The unique thing about this rain:

only occurs where there is a really high mountain or a mountain range
only rains on one side of the mountain (the leeward side). It doesn't rain at the rain shadow/windward side. Why? Well simply because there is little or no moisture here, the air then sinks and heats up.
take a look at the Himalayan and Andes mountains, notice how there are deserts found there.

2. Frontal Rain

NOTE: warm air and cold air do meet but they do not mix, so what happens when they meet? Well, since cold air is denser than warm air, the cold air will sink, forcing the warm air to rise, we then get adiabatic cooling. After which clouds and rain form.

Unique thing about this rain:

only found at temperate regions, because this is where the cold air from the polar regions meet the warm air from the tropical regions.

3) Convectional Rain

Note that for convectional rain, the sun does not heat up the air. What happens is, the sun heats up the ground (land) the land then heats up the air. The warm air then rises and once again we get adiabatic cooling, after which clouds and rain form.

Unique thing about this rain:

found at tropical regions as it is sufficiently warm there.
- normally occurs during the afternoon to evening, why? Well cause thats when the sun is up. It doesn't occur during the day time, as the ground isn't hot enough to heat up the land. But then why is it we experience rain in the daytime sometimes? Well thats monsoonal rain and I'm not about to get into that.

We'll that's basically it. Enjoy! Oh and for those guys who missed out on all the FUN during lesson, here;s a little video, though i don't think you can see much.

meera

Mr. Sunbeam is trapped! :O

2009-02-09T19:58:00.002+08:00

So Mr Heah let us watch The Inconvinient Truth by Al Gore today. :D So I shall try to pick out the main points from the video, since some of you *ahemahem* fell asleep during the video! haha. xD

So basically, the video talks about global warming and how it's affecting us. So here's a quick recap on what global warming is (although you should know fully well by now):
The Earth is made up of a thin layer of atmosphere. It's so thin that its like you painting a coat of vanish onto a globe and the atmosphere is represented by the varnish. So you can imagine how thin the atmosphere is in relation to Earth. So when the atmosphere gets thicker, the air composition also changes, which means that more greenhouse gases are in the atmosphere and more heat is trapped! So in the video, Al Gore showed a cartoon to represent global warming and there it is! Heh. xD

So after watching this, you should have a rough idea on why the Earth is getting warmer and warmer.

So Al Gore goes on to explain why there are high and low points on the carbon charts. And this is due to the fact that there are more vegetation in the Northern Hemisphere as most of the landmass is in the Northern Hemisphere. So drung Spring and Summer, the Northern Hemisphere is facing the sun, so the plants will take in more carbon dioxide for photoshynthesis thus causing the carbon dioxide level to drop. Then when it's the Southern Hemisphere turn to face the Sun, the plants release more carbon dioxide due to respiration and a lower rate of photosynthesis. However, there is a steady increase in the amount of Carbon dioxide in the atmosphere over these few years. And so when the amount of carbon dioxide increases, the higher the temperature, as illustrated in the video above.

As Mr Heah always say, there is always a cause and effect for everything. So what's the effect of global warming?
-Glaciers are melting. If you watched the video, it's kinda scary to see the rate this HUGE, GIGANTIC glaciers are melting at.
-Many mountains like the Alps, Mt Kilimanjaro, etc have no more/little snow at the peaks anymore as they are melting at a super fast rate as well.

You may think, so what? This doesn't really affect us, after all we're living in Singapore and those glaciers and mountains are mostly at the other end of the world. But you're wrong! Places like Greenland and West Antartica have lots of land-based glaciers which are starting to melt. And if half of Greenland and half of West Antartica glaciers melt, the sea levels will rise about 20 feet ALL around the world. Thats like ALOT ALOT of extra water. And Singapore being an island surrounded by open seas, we're most likely going to go underwater as well. Places like San Francisco, Beijing, Shanghai will all be affected as well. Billions of people are going to lose their lives cos of global warming.

So I'll just backtrack abit. If you're wondering how those ice glaciers melt so fast, its cos when sunlight hits the ice, 90% of the heat is reflected back to space. HOWEVER, when the sunrays hit the open waters surrounding the ice, 90% of the heat is absorbed, causing the surroundings to get warmer, thus causing the ice to melt at a faster rate. So it is really important for us to come up with ways to stop global warming. hopefully this will help your Geog Essay, which is due next monday, a little. (:

So I'm done summarising (ok fine, it's kinda long) today's lesson. Now i have to write my answer for the geog question on the yellow paper. And if you think you can copy my answer, GET THAT IDEA OUT OF YOUR HEAD NOW! Cos seriously, i don't do well for such questions. But we learn and improve on our mistakes. ;D

Qns: To what extent should we be concerned about the CO2 emissions?
Ans: We should be veryconcerned about CO2 emissions as it has many harmul effects on us.

Firstly, when too much CO2 is emitted into the atmosphere, it will case global warming to happen as the CO2 will trap the sun's heat and prevent it from going back to space and thus, the global temperature will gradually increase. When the global temperature increases even by as little as 1 degree celsius, the ice glaciers at the North and South pole will melt rapidly. This will cause an increase in the water levels all around the world and many places will be flooded.

Secondly, when we emit too much CO2, it will cause Climate Change. Climate Change will affect all of us. Examples of climate change can be seen in the news these days. For example, Melbourne, Australia is experiencing the hottest summer ever with temperatures rising up to as high as 46.5 degress celcius. While in places like China, certain places are experiencing severe flooding while parts are experiencing severe drought. This shows that Climate change has a negative impact on us.

Therefore, looking at the severity of Global Warming and Climate Change caused by CO2 emissions, we should be very concerned at the amount of excess carbon dioxide we're emitting into the atmosphere as it has severe impacts on us and the environment we are living in.

That's all,
-Amelia ;D

2009-02-06T23:58:00.003+08:00

At the start of the lesson, Mr Heah did a revision of what we had done last week.

Firstly, he talked about systems and that all systems must have a balance, equilibrium or in biology terms, homeostasis. When the system is not at equilibrium, either a negative or a positive feedback occurs. Negative feedbacks discourages change and hence the change would be stable. Positive feedback encourages change and hence the change would be unstable.

Then Mr Heah started talking about the main gist of our lesson, which was on thermodyanic equilibrium.

Heat transfers in 3 ways: conduction, convection and radiation.

The range of visible light: Red Orange Yellow Green Blue Indigo Violet

Short wavelengths -------------------> long wavelengths

cool ---------------------------------------> hot

low energy ------------------------------> high energy

The sun emits long wavelengths and the Earth emites short wavelengths.

So, what does thermodynamic equilibrium mean?

It simply just means heat gained by the Earth, must be equal to the heat lost by the Earth.

However, due to an excess in greenhouse gases, we are losing less heat because greenhouse gases trap heat within the atmosphere.

Mr Heah then talked about CO2 which is a greenhouse gas. CO2 absorbs long wave radiation but allows short wave radiation which comes from the sun to pass through. So greenhouse gases actually act as a heat blanket for the Earth.

Global warming is due to the building up of more greenhouse gases which then traps more heat.

To see exactly how much heat is gained and lost and in what ways, Mr Heah got us to draw this diagram. It shows exactly how much heat is gained and lost and how if the Earth gains 100 units of heat.

That's all for now (:

-audrina

Geo lesson for 2nd.Feb! ^^

2009-02-02T23:41:00.005+08:00

When today`s lesson just started, Mr.Heah tried to remember our names.~_~
And then was the revision part. We reviewed some points including composition of atmosphere, function of Oxygen Carbon dioxide and Nitrogen.
Following we talked about systems equilibrium and regulatory forces witch include positive and negative feedback, positive feedback will cause encourages change while negative one will cause discourages change.
Next is the most important part we had for this lesson: Carbon Cycle! "What is the impact of man on carbon cycle?" Mr.Heah said it was very important to ASK QUESTIONS ABOUT THE QUESTION! So we need to consider about "What is/are the impacts?" and "What is carbon cycle?". And here are the mind map of carbon cycle.:)

Umm sorry maybe not clearly enough...

Ok that`s all for today.
Xue^_^lu

GEOG LESSON! 30.1.09

2009-01-30T22:52:00.004+08:00

This is basically a miniature version of the mindmap Mr Heah wrote on the board (: So this lesson, we were taught how to answer questions like the one above "How is the atmosphere essential to life", topics which are very broad and require lots of compressing. So it goes like this:
1. Remember only relevant and important knowledge from the provided readings and text. Most of the stuff above is general knowledge, so no need to get into technical details.
2. Organise relevant information into a mindmap, like the one above. Keep the points simple and direct. Placard mugging is highly discouraged.
3. Length of answers should be directly proportionate to the number of points of the question. Therefore, no essays for 5 mark questions.

We watched a documentary later on, and I shall try my best to summarise its main points.
1. The atmosphere is made up of the four main layers, each with its own properties that makes it a protective and life-giving shield. A general summary can be found in the mindmap.
2. The atmosphere is a fluid, not a layer of random gases. This was illustrated by the cool 'wind'surfing guy, and the rock formations caused by wind and sand. (Apparantly, the weight of the atmosphere is pushing down on us, 13 pounds per square inch)
3. The gases in the troposphere enables us to carry out life processes, mainly referring to Oxygen and Carbon dioxide, which we need for respiration and heat retention respectively. And the lack of oxygen leads to miscarriages O.o
4. The history of the atmosphere was also explained, tracing back to 4.4 billion years ago, when the gases escaped from the volcanic material on earth. The earth was rich in carbon dioxide and other greenhouse gases, causing bacterial organisms to thrive. Later on, the oxygen they produced in large quantites enabled us to evolve.
5. As the Global Warming issue was raised at the end, and they revealed a shocking revelation that the Carbon dioxide problem was not as serious as the methane problem! Many tonnes of methane (which is a lethal greenhouse gas) are trapped in permafrost in the freezing regions of the earth, and global warming is causing the release of this gas!
We will most probably end up like the bacterium anyways (:
Just as a note (to fulfil the conditions of the blog assignment), I feel that the mindmap part of the lesson was the most important part, although the Stewart person was beneficial too.

Well, that's it! Cindy (:

Reflection

2009-01-19T21:12:00.002+08:00

During today's lesson. We learnt about structure and composition of atmosphere. Generally it is made up of 78% of nitrogen , 21% of oxygen and 1% of other gases like carbon dioxide and water vapor, etc. And the reason why atmosphere is essential to life is because it exerts a suitable pressure, provide oxygen which is essential for life and shielding us from sheer heat from the sun, enable sunlight to go through it and thus plants will undergo photosynthesis and provide food for us.
Chen Xingru