IS2104: Atmosphere and Hydrosphere

Reflections

Carbon Cycle and Greenhouse effects June 24, 2010

Filed under: Uncategorized — 09ip01 @ 11:44 pm

Hi 01! 

Since this reflection is late already and most of the modules have been covered previously. 

Thus, I shall spend my part on carbon cycle together with Greenhouse effect. 

The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. 

It is one of the most important cycles of the earth and allows for carbon to be recycled and reused throughout the biosphere and all of its organisms.

Carbon exists in the nonliving environment as: 

—carbon dioxide (CO2) in the atmosphere and dissolved in water (forming HCO3−)

—carbonate rocks (limestone and coral = CaCO3)

—deposits of coal, petroleum, and natural gas derived from once-living things

—dead organic matter, e.g., humus in the soil

Carbon enters the biotic world through the action of autotrophs: 

—primarily photoautotrophs, like plants and algae—use the energy of light to convert carbon dioxide to organic matter. 

—to a small extent, chemoautotrophs—bacteria and archaea

Carbon returns to the atmosphere and water by 

—respiration (as CO2)

—burning

—decay (producing CO2 if oxygen is present, methane (CH4) if it is not.) 

Unfortunately, the extent of its importance is rarely stressed enough. 

Without the proper functioning of the carbon cycle, every aspect of life could be changed dramatically.

Carbon dioxide is transparent to light but rather opaque to heat rays. 

Therefore, CO2 in the atmosphere retards the radiation of heat from the earth back into space — the “greenhouse effect”.

Has the increase in carbon dioxide led to global warming?

Average temperatures do seem to have increased slightly (~0.6°C) in the last century.

Some evidence:

—Careful monitoring of both ocean and land temperatures.

—Many glaciers and ice sheets are receding.

—Woody shrubs are now growing in areas of northern Alaska that 50 years ago were barren tundra.

—Many angiosperms in temperate climates are flowering earlier in the spring than they used to.

—Many species of birds and butterflies are moving north and breeding earlier in the spring.

-Xiye

 

Filed under: Uncategorized — 09ip01 @ 7:36 pm

Somehow I didn’t receive any email which I was supposed to receive; thus I wasn’t informed to finish my IS2104 journal until yesterday when I get back to Singapore. It seems that our reflection has covered all the topics we have learned, I just simply do a summary and talking about my confusion.

In first few units, our minds are impregnated with an idea which is Earth is a living system. We studied composition and structure of atmosphere, and the importance of keep the system in equilibrium. With this fundamental knowledge, we started to learn the function of atmosphere and carbon cycle. Atmosphere is so amazing that it balances planetary energy, carbon cycle explains the reason of global warming. In unit 3, we studied that the sun drives many of earth systems, because sun provide us with knowledge. Then, we learned climate of the world, which is determined by the shape of earth, varied terrain and so on. In unit 5, we finally enter the world of water. It is so magical that a unit can be summarized in one equation, P=Q+E+ S. Mr heah lead us to the centre of our school which is a small  pool, to make us understand the concept of drainage basin. During the class, we appreciated many beautiful pictures while we are studying water fall, river and other phenomenon about water. Anyway, I love this part most though my grades are not high. I didn’t do every well in this module, too many concepts must be remembered, and construct a memory system is not that easy.

Very sorry about this latest entity

Chenxi

 

River Deltas, Valleys and Floodplains

Filed under: Uncategorized — 09ip01 @ 6:46 pm

Hi 01,

I’ll be talking about the formation of river valleys, deltas and floodplains.

River Valleys

As the name suggests, river valleys are valleys whereby water flows through. Valleys are one of the most common landforms on the Earth formed by erosion which is the gradual wearing down of the land by wind and water. In river valleys, the river acts as an erosional agent by grinding down the rock or soil and creating a valley. The shape of valleys varies but they are typically steep-sided canyons or broad plains. There are many factors which affect it such as what is eroding it, the slope of the land, the type of rock or soil and the amount of time the land has been eroded. Most of the time, these valleys are v-shaped.

An example:

File:BlackCanyonNP L7 12sep00.jpg  

 -Black Canyon of the Gunnison National Park at Western Colorado

River Deltas

Deltas are the result of interacting river and marine systems. They can form anywhere a stream flows into shallower open water. When sediments are deposited at the mouth of the river after a long period of time, deltas are formed.

 -The Mississippi River Delta

Floodplains

Floodplains are a natural feature of rivers.  They are the mostly flat land adjacent to the river and form due to the actions of the river. Floodplains are essential for us as:

  a) reduces the number and severity of floods

 b) minimizing non-point source water pollution

 c) filtering storm water

 d) providing habitat for plants and animals

 e) aesthetic beauty and outdoor recreation benefits.

An example of a flood plain:

 – River Dordogne in France

Ok, that’s all! See you guys in school next week:D

– Sijia

 

Potholes, Waterfalls and Rapids June 23, 2010

Filed under: Uncategorized — 09ip01 @ 4:17 pm

Hey everyone,

There hasn’t been a post for some of the river landforms yet, so I’ll be doing a post on the formation of potholes, waterfalls and rapids. There are others like river valleys, braided rivers, deltas and floodplains you can still do.

Potholes

The first thing that comes to mind is probably the potholes we find in the middle of the road. River potholes are somewhat alike. They are holes along river beds. Of course, what we need to know is how these are formed.

How potholes are formed

So a river bed starts off with possibly a small natural crack. When small rocks and pebbles get caught in a circular motion, like a whirlpool, it causes a drilling action into the river bed at that crack. It is a drilling action because there is abrasion between the small rocks and the river bed. Over time, this drilling action continues, and forms a pothole. The size of a pothole varies, mostly depending on the amount of time the drilling action occurs. They can be many centimeters wide and deep.

Bourke's Luck Potholes, Blyde River, South Africa

Waterfalls and Rapids

We have seen waterfalls many times during movies, where there are people on a river, falling down a waterfall. But somehow they survive, falling behind where the water is flowing down. They find a secret cave, or someone meditating. But why exactly is there space there so that they’re not drowning in the water?

How waterfalls and rapids are formed

Waterfalls are most likely formed when a river is young. The riverbeds of waterfalls have hard, resistant rock, and softer less resistant rock. The river will erode the softer rock faster, while most of the hard rock will continue to stay in its place.  Eventually, all the soft rock will get eroded, leaving the hard rock to form a ledge. The water from the river would then fall steeply, and its motion would erode the soft rock at the bottom as well. This motion forms a plunge pool. Overtime, the pressure of the waterfall will cause the hard rock ledge to break off, and this process will repeat itself.

It may be hard to understand through prose, so here’s a video that can help you understand this phenomenon. http://www.youtube.com/watch?v=HcJ7BKWyy_w&feature=related

Rapids are a smaller scale version of waterfalls. They are equivalent to small steps along a river, that carry strong turbulent waters.

So how are potholes, waterfalls and rapids related?

Hydraulic action is required to cause the drilling action that forms potholes. Waterfalls and rapids provide this hydraulic action, from their turbulent waters. Therefore,  potholes are most likely to be found below waterfalls and  rapids.

Yeap that’s about it. Enjoy the last few days of holidays if anyone is reading this!

– Xin Yi

Havasu Falls, Grand Canyon

 

Meanders and Oxbow Lakes

Filed under: Uncategorized — 09ip01 @ 3:31 am

Hey guys! I’ll be posting and elaborating more about the Prezi presentation that we had with Mr Heah during one of our last few lessons!

Meanders are curves or bends along river courses. They usually occur in the lower and middle course of the rivers where floodplains are located. Meanders are formed by a combination of three processes, namely erosion, transportation and deposition along a river.

Erosion (specifically via a combination of abrasion and hydraulic action) occurs on the outer banks of a meander, this is so as the river has greater energy here and the small rocks and sediments gets carried along with the flow of the river and over time, it gradually wears away the meander’s outer banks. However, in the inner banks of the meander, the river’s energy is significantly weaker. Over here, the small sediments carried by the flow of the river are deposited onto the inner banks of the meander.

Over a long period of time, the two ends of the meander will eventually join, effectively creating a meander cut-off, also known as an oxbow lake. The oxbow lake may eventually dry up due to evaporation or it may become active parts of the river system when a flood occurs. The oxbow lake may also provide growth of vegetation or provide habitats for the biodiversity.

Pictures illustrate how a meander is being cut off, forming an Oxbow lake.

 

  

  

  

Here are some pictures of meanders around the world! 

Arda River meander, near Ürpek, Bulgaria

 

Hope you guys enjoy the last week of holidays! Cya in school soon;D
-Meredith:D

The aerial view of Usumacinta meander in Guatemala through the Lacandon Forest

 

Sustainable Singapore June 21, 2010

Filed under: Uncategorized — 09ip01 @ 11:31 pm

hey all, Teresa here :D Sincerely apologise for the rather late entry, was unable to access my hotmail for the past few days. And hopefully this entry is still valid?😀

 I’ll be posting about the project which sums up the entire module, Sustainable Development. Through both the individual and group assignment I guess we all learnt much more about how to build and foster a sustainable community. This is especially important in Singapore due to it being a small city with very few natural resources. And it is especially especially important now because:

1. There is a need to manage the growth of our city (having more housing estates, industries, roads and at the same time keeping our city state clean and green)

2. Resources are getting limited and scarcer worldwiden (we import and depend largely on other countries and due to scarse resources, cost have been rising which will affect our growth and development)

3. Climate change (everyone plays a part in combating climate change!:D )

Of course this is what have been drilled into our minds since we’re born; “Earth is our only home”; “Earth is fragile”; “Save the dying Earth!”. But I believe the purpose of the project is much more, it is to let us learn how to actually make a difference and change our livestyles, and defintely, how difficult it is for the to-day architects to design and make a blueprint of a 100% self-sustainable island.

We live in a society that with a touch of the switch we call electricity to us, with a turn of the taps water magically appear. And this is the reason why we take much of these resources for granted. After going through this project, I’ve indeed been exposed to much more. About being energy efficient, about water conservation, about recycling etcetera. Instead of listing out how to achieve all of those (I’m sure we all already know how to), I would rather like to remind all of us about how our government has been trying to promote conserving our environment:

1. Do you know the purpose of the real-time bus arrival thing in bus-stops are to make public transports more convieniet and encourage people to take buses?

2. Do you know about the RAIN GARDERN in Balam Estate?

3. Do you know there is a Singapore International Water Week?

To be honest I din’t know either until the project😀 haha. So, if even the Pulau Ubin old uncle and aunties can put up a great fight to preserve the natural habitat of Chek Jawa, I’m sure we’ll be able to do something more to “Make Singapore a livable & lively city state, one that Singaporeans love and are proud to call home”.

TERESA😀

 

June 19, 2010

Filed under: Uncategorized — 09ip01 @ 4:15 pm

Since every one has already written something about mr Heah’s lessons, I shall write my reflection about how can I use the knowledge in the module to help me explain some of the weather phenomena here in Vietnam.

When I link all the knowledge that mr Heah taught us about the wind direction, humid air, and all the mountain ranges blocking the wind resulting in rainy weather at one side and desert at the other side.

You guys can refer to the picture below to understand what I’m talking about.

Erm you can ignore those Vietnamese words as I can’t find any picture that is in English. You can see the arrow representing wind blowing from the South East up to North West. That wind brings humid air from the ocean inland.  And you can see the moutain range in yellow  ( it’s called Truong Son fyi ) in the picture below, blocking the wind mentioned, then on the right side of the range there’s fine weather with rain and nice food. But on the left side the weather is dry and harsh.

It’s just like the Andes in South America mr Heah talked about.

I’ve never thought much of how geographical positions can affect the weather and climate like that. After the module and when I come back to Vietnam, I just realized how much they are interconnected. Just like Hanoi (the North of Vietnam) can get as cold as 10 Celcius degree or even lower, while in Ho Chi Minh City, all the way at the South of Vietnam, the lowest it can get is not even 17 degree.

Okay that’s it for my reflection.

-Khue