Tilt and Shape (23 Feb)

MAK (IE TING AMANDA) SAYS HELLO. :D

So I’m here to post on today’s lesson. Basically, the lesson was spent answering, or trying to figure out the answers for two questions.

1. Explain the distribution of Earth’s climate.

2. Why are there seasons?

Miss Lin split us into groups of threes and fours to discuss. Like, some of us were supposed to work on the first question while the rest had to do the second. Some of us were told to present our answers on the board but we weren’t that clear, so Miss Lin ended up explaining instead.

We referred to the colourful world map given to us a few lessons ago to answer the first question. It can be seen from the map that at the Polar Regions, the climate is much colder than at the Equator. Reason being, the radiation from the Sun is being spread over a larger area when shone at the Earth’s surface at the poles than at the equator. The diagram below should give you a better picture.

So, as you can see, supposedly six rays hit upon Earth - three at the North pole and three at the equator. The intensity of sunlight does not decrease due to the distance but the rays are like, spread out at the pole. So the concentration there is lesser as compared to the equator. Therefore, it is hotter at the equator! Yeah, it's something along these lines.

We learnt that this uneven heating is known as differential insolation. Insolation refers to the amount of solar radiation energy received on an area in a given time.

Okay, then Miss Lin drew another diagram to aid our understanding on the distribution of the Earth’s climate.

I only drew the Northern Hemisphere because it looks neater. :D
(I hope the diagram's correct..)

Okay fine, I'm a little lazy too but yeah. As long as you understand how the convection currents at the Northern Hemisphere work, you will understand how the Southern works too. The principle is the same, just flip the Northern Hemisphere over, using the equator (where the words "Low Pressure" are at) as the line of symmetry, and you will get your Southern Hemisphere.

I think it's damn cool to have different names to the convection currents at different parts. Besides that, I made a brief explanation on what happens at the Polar Cell. If it's too small, maybe you can look at it here.

High Pressure --> Air cannot rise --> No clouds formed --> No precipitate --> No water --> Desert --> At the High Pressure Belt.

As the air at the North pole is cold, its density is really high and therefore the air has high pressure. So, the air can't possibly rise and form clouds. Without clouds, you can't get rain yeah? And no rain means no water. If there is no water over a long period of time, the land will be dry and tata, you get your desert at the High Pressure Belt!

I guess this answers today's commonly asked question: How come there are deserts at the Tropic of Cancer/Capricorn and not at the equator?!

Also, we learnt that there are seasons because the Earth receives different amounts of sunlight at different times. Thus, during the first half of the year, the Northern Hemisphere which is tilted towards the Sun will be warmer as it receives a greater amount of insolation, while the Southern Hemisphere receives lesser insolation. The Northern Hemisphere will experience summer while the Southern Hemisphere experiences winter. Basically, during the later half of the year, the Northern Hemisphere experiences winter and the Southern Hemisphere, summer. This cycle goes on and on. And so, we have the four seasons. The equatorial countries do not experience the four seasons as the equator is where the subsolar point is. The subsolar point is the point on Earth where the Sun’s rays meet the surface at a right angle, with no change in the amount of solar radiation received throughout the year.

I’d say this lesson is pretty interesting. I mean, we get to understand how deserts become deserts. So if you actually have those fantasies of a giant blowing away all the water and drying up a piece of land to make it a desert, you should now realise that the giant does not exist. So the reason why the Earth’s climate is like this is all due to the convection currents in our atmosphere. The rising of hot air and the sinking of cold air cause the difference in air pressure which in turn causes the convection currents.

It is also amazing to find out how much a degree change in latitude or longitude can affect the amount of sunlight received. In our daily lives, I doubt a degree change actually means anything to anyone; it seems so insignificant. But wow, things are indeed different out in space.

So yeah, that’s about all for today! I hope this isn’t too screwed. :D

Rain Formation

BASIS OF RAIN

So, rain formation. It's the formation of rain! How? The basis of it is that when hot air rises, the pressure would decrease resulting in expansion and then the cooling of water molecules. ---> RAIN This is done by the gases in the atmosphere which causes each molecule to lose energy.
There are three different types of rain. Convection rain, orographic (yes its the correct spelling) rain and frontal rain.

1) Convection Rain - Rain caused by the cycle of evaporation and condensation on the clouds (nothing special)



2) Orographic Rain - Rain caused by natural forces of its surroundings. (usually appears at hilly regions and mountains)


3) Frontal Rain - Rain which is created by the collision of two fronts made of different air masses, the warm front (warm air) and the cold front (cold air). The cold front would "subduct" under the warm front just like how plates subduct under each other.


Reflection
I found the lesson on the formation rather dull as it was rather common sense that how rain basically forms. The only problem is that we do not know what the names of the rain are called. For example, convection rain is basically what we learnt in like primary school. However, the other two types of rains were pretty new and interesting to learn about. Also, there was also a part which mentioned something about the physics of the system of geography which we are all learning about. Didn't find it very important though and I don't think it would be tested until a very very long time so I ignored it and slept through that part :D. (woke up 5 mins later and found out lesson ended anyway)



Nigel Tan JH404

REFLECTION FOR 9th FEBRUARY GEOGRAPHY LESSON
by Ng Shou Jin.

So today we just got a new 8 mark assignment with the question as: To what extent should we be concerned about carbon dioxide emissions? After which, we watched a DVD on Al Gore and his dedication to climate changes and due to that, he won a nobel prize due to his works.

Now, who is Al Gore? He is an American environmental activist who served as the 45th Vice President of the United States, and has been in the political line for quite a long time. He presented a documentary on global warming and climate change called An Inconvenient Truth; one that was inevitable yet is the cold, hard reality of the state of the world which is falling. He was working to try to get the message across to as many people as possible about the falling state of the world, and that we humans are the major factor of its impending downfall.

Atmosphere
The atmosphere that protects the Earth is actually vulnerable as it is a thin film over the Earth, and the major disadvantage of ts thin-ness is that it is actually thin enough for human beings to change its air composition. Up above is a picture I have amateurly drawn on paint to illustrate how the atmosphere traps heat as well as reflect heat to keep the Earth's temperature just right for us to live in. Ive added in the text in the picture as well to explain how the atmosphere ensures a desirable environment for us to live in as well, as explained by Al Gore.

What air pollution is doing to the atmosphere is actually to THICKEN the atmosphere, and thus the infrared radiation trapped in the Earth does not easily escape to space, and this would then cause our problem of global warming. He also gave an analogy where the leaves also contribute to the carbon dioxide cycle which maintains the carbon dioxide cycle. During Spring and Summer, when the sun is at it brightest, the leaves of trees would 'inhale' carbon dioxide for photosynthesis; but they would 'exhale' carbon dioxide as well in Autumn and Winter where light is scarce, and the leaves would be decomposing to form carbon dioxide. Through this, carbon dioxide is repeatedly maintained at around the same levels.

However, now that the carbon dioxide level is much higher than those expected of from the last few centuries [where 300 parts per million is way too high already]. Al Gore also provided us with one of the most important concept, where

More CO2 = higher temperature,

because CO2 traps heat in Earth

That's about it for today's lesson! My conclusion for this is that we have to be concerned about carbon dioxide emissions to a high extent.

REFLECTION:

If I hadn't attend this lesson, I would not be aware that such a dedicated and passionate environmental activist called Al Gore existed. In addition, I had not really been clear of what negative things greenhouse gases like carbon dioxide do to the atmosphere as well as how it contributes to global warming. It makes me more aware for what we humans are constantly doing to promote further global warming in the Earth, like the careless burning and usage of fossil fuels or the neglection of the negative impacts of deforestation for cultivation in Indonesia etc. Greenhouse gases, in fact, are the ones responsible for trapping heat in the Earth and if it thickens the atmosphere, our Earth would get heated up.

-End.

Planetary Heat Balance

Planetary Heat Balance

So what is the planetary heat balance???

Basically it is a system that needs to be in balance otherwise the Earth would either freeze or burn.

(If one day the system is not in balance, I prefer being freezed to being burned, I hate hot weather ^^)

The note is very long and complicated to read every single point in it so that I will summarize the most important points :

Shortwave radiation from the Sun enters the surface-atmosphere system and is ultimately returned to space as longwave radiation.

There are 3 main losses of solar radiation back to space .The sunlight is returned back because of

1. Surface reflection

2. Cloud reflection

3. Back scattering

There are also 3 main processes through which the energy leaves the Earth’s surface

1. The heat may leaves as sensible heat ( sensible heat is just a kind of heat that can be felt) => atmosphere by convection and conduction

2 & 3.The melting and evaporation of water transfer energy into atmosphere as latent heat

Personal comments on the lessons and the note :

I’m sure that we will find all the data provided in the note very hard to memorize and you will wonder why we have to learn all those data.

Oh, the reason is simply for you to understand roughly how much energy is transferred in and out of the Earth.

However, I personally think that all those numbers are just making just more and more confused. Those values of energy cannot be constant because if they were constant then there would be no climate change today (so good right ?!). Those values depend on a lot of other factors such as CO₂ concentration, the thickness of the Ozone layer…etc… Therefore, I think you don’t need to remember all those value, you just learn the processes and understand them as a system. Forget all the Values.

One last comment about the method of the teaching is that drawing the whole system on your own is a really useful technique to study since you can explore your ability to really learn by yourself. At the same time you also learn how to analyze the information in the passage and how to synthesize them into a diagram.

Yeah, that's all for today lessons. One more time, LEARN IT AS A SYSTEM!!!!!!!!

We were told (more than ten times) NOT to memorise any knowledge, but to understand everything in systems.
A system has regulatory forces, and these forces are known as positive or negative feedback.
A negative feedback is something that discourages the change. For example, when you exercise, your body heats up (the change), but you sweat, which cools your body down (the negative feedback). And negative feedback can be good, even if it's negative.
A positive feedback is a reaction that encourages the change. For example, water vapour is a greenhouse gas, so it will trap heat from the sun and cause the Earth to heat up. Because of this, more water will evaporate, and then more water vapour will built up in the atmosphere, causing the Earth to heat up further, which causes more water to evaporate and so on and so on and so on.
Then, we talked about the Carbon Cycle. This is a drawing of it. (The words are microscopic, so you may have to squint and guess.)

The black arrow labelled burning (if you really can't ready microscopic print), was caused by (guess who?) us human beings. That is why there is an increase in the amount of carbon dioxide in the air, which has led to the enhanced greenhouse effect. (This is a hint for our Climate Change essay, if you are talking about reducing carbon emissions)

The real reflection:
I thought the Carbon cycle was really interesting, because it was an example of how Mother Earth is completely made up of systems. Besides the Carbon Cycle, there is the Nitrogen Cycle, and the Water cycle, etc. Everything is somehow positioned perfectly so complement each other. For example, we do not need to worry about a shortage of water when we see the sea water evaporating, because it falls back down as rain again, and no water is actually lost. How the Earth is so flawlessly programmed amazes me.
(During this lesson, we also learned about how we needed to do an essay on Climate change.)

Goh Yi Sin JH404