♥ Friday, May 29, 2009 ♥
Heyhey!
Sorry for the lag post and all :/
Anywayyy! Time to summarise the entire module! Basically, we covered 2 major spheres in this module: atmosphere &hydrosphere (:
For atmosphere:
Basically, we learnt about the composition of air -78% nitrogen, 21% oxygen and 1% other gases and learnt how oxygen is important to sustain life because it is reactive and forms compounds with various elements, allow humans to use it for respiration and life processes. Such a composition is ideal to sustain life.
Later, we learnt delved deeper into the presence of carbon dioxide in the atmosphere (0.03%) though the carbon cycle. Basically, we learnt that carbon dioxide is taken in by plants, then, as the plants & animals decompose, they give off carbon. Also, as they respire, carbon dioxide is given out. If dead plants & animals do not fully decompose they will form fossil fuels, storing carbon in the earth. Carbon dioxide is dissolved in the ocean as well, providing aquatic plants with energy. From this, we realize that plants & animals give off carbon when they respire and decompose, while plants take in carbon dioxide via photosynthesis and carbon dioxide is absorbed by the ocean as well to allow aquatic plants to respire.
We also learnt how man’s actions have interfered with the carbon cycle, thus, resulting in an increase in global warming as well. E.g. deforestation: results in less trees and thus, less carbon dioxide is removed from the atmosphere, increasing carbon dioxide levels and thus, increasing the amount of greenhouse gases, thus, resulting in global warming.
Then, we went on to learn about rain: frontal, relief and convectional rain. Essentially, frontal rain occurs when either warm air meets a cold front, or when cold air meets a warm front, resulting in the warm air rising and thus, adiabatic cooling occurs and it rains. Relief rain occurs when air is forced to rise when it meets a relief (e.g. mountain) causing adiabatic cooling, and rain to form on the windward side (facing sea) thus causing the leeward side (facing away from sea) to be dry. This may allow for the formation of deserts. Lastly, convectional rain is simply warm air rising and thus resulting in adiabatic cooling, and thus, rain. (:
Then, we learnt how to interpret climographs. Basically, its just describing how warm&wet a place is based on the data provided.
From the lesson on climographs, we realized that different countries have different climates, why is this the case? This is where the global air circulation model comes into play. Essentially, the global air circulation model looks like this!
which then results in the various different climates in the world, as well as the formation of deserts between the hadley cell and the ferrel cell. This is because air at the ferrel cell moves upwards while air at the hadley cell moves downwards, resulting in no adiabatic cooling occuring, and thus, no rain formation, making that area dry, and thus, forming a desert. * deserts are also formed due to relief rain (:
essentially, that concludes the atmosphere component!
:D:D:D
....now moving onto the HYDROSPHERE, which will be continued in the next post.
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♥ Sunday, May 3, 2009 ♥
Ok, right, time goes by and it was my second time to write the post.
In the 30 minutes lesson, we have learnt about the WATERFALL and MEANDER.
So let’s begin with the waterfall. The waterfall is a steep descent of water from a height. It usually found in the upper course of a river in the hills or mountains.
A WATERFALL=A STEEP DROP OF WATER
Formation of Waterfalls:
--It forms when a band of hard resistant rock lies over softer, less resistant rock.
--The softer rock is quickly eroded by hydraulic action and abrasion, causing the harder rock to be undercut.
--The hard rock overhangs until it can no longer carry its own weight.
--The overhang collapses and then breaks up in the water below.
--The great power of the water at the base of the waterfall causes a plunge pool to form.
--The bed of the river below the waterfall contains boulders eroded by splash back from behind the waterfall.
Some Facts of Waterfalls:
The tallest waterfall in the world is the Angel Falls. It is 979 metres high.
The highest waterfall in Africa is the Tugela Falls at 947 metres. It is found in South Africa.
Europe's highest waterfall, Utigard in Norway, is 800 metres high.
The Yosemite waterfall (739 metres) is the highest waterfall in the USA.
Secondly, we learnt meanders which are curves or bends along a river. It is usually found in the middle or lower course of a river.
MEANDER=A BEND IN A RIVER
Formation of Meanders:
A meander is formed when the moving water in a river erodes the outer banks and widens its valley. A stream of any volume may assume a meandering course, alternatively eroding sediments from the outside of a bend and depositing them on the inside. The result is a snaking pattern as the stream meanders back and forth across its down-valley axis.
Cause of Meanders:
Helicoidal Flow=Spiral Movement of Water
It will move eroded river load from the outer bank and then deposited much of it on the next inner bank of a river.
Top current: hits against the river bank and undercuts the eroded material.
Bottom current: carries the eroded material and deposits them in the next inner bank.
Yeah, I guess it’s all. Hope you can understand.
Enjoy the half day, heh heh.
Done by Violet
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