How human beings alter the atmospheric energy budget


In our earth, all the energy comes from the sun. This is known as the radiant energy which keeps the earth warm enough to live. The earth’s mean temperature changes only slightly from one year to the next. This

is due to the fact that the earth maintains a balance between radiation gain and radiation loss. But with human intervention, the earth’s atmospheric energy budget is seriously affected.

First of all, the earth can only have one way of incoming heat energy, which is radiant energy. When the solar energy reaches the earth surface and the atmosphere, some of them are absorbed by the earth atmosphere system, while some energy is reflected or scattered back to space. The energy absorbed is the income of heat to make the earth warm. The heat is absorbed by the earth and atmosphere through many ways, such as direct solar energy absorption to the earth surface, atmosphere and clouds, latent heat transfer, sensible heat transfer and net gain from surface which is the gain from surface radiation minus the loss by counterradiation. After the energy is absorbed by the earth-atmosphere system, the energy is lost back to space from the earth also by many ways like long-wave terrestrial radiation, latent heat transfer and conduction and convection.

Radiation gain of the earth-atmosphere is equal to radiation loss on a global scale. But radiation gain seldom equals radiation loss on a regional scale. There are always regional net surplus or regional net deficit. The receipt of energy differs from regions is because of many reasons. Firstly, it is the difference of the length of daylight. If a place receives a longer (smaller) length of daylight, the amount of absorbed energy will be larger (smaller). Then, it is the difference of nature of surface (degree of reflectivity which is known as albedo). If there is wet dark soil in a place, the degree of reflectivity is low, the amount of absorbed energy will be large, but if there is fresh snow cover, the degree of reflectivity is high, so the amount of absorbed energy will be small. Also, there is different amount of cloud cover on different places. More amount of cloud cover will result in larger reflection of radiation and larger absorption of radiation by the cloud, so the amount of radiation reaching the earth will be smaller, or vice versa. Lastly, it is the latitude of places. (affects the angle of incidence). Lower latitude areas have larger angle of incidence, resulting in more receipt of energy, but in high latitude areas, the situation will be opposite, the amount of receipt of solar radiation will be less. Because of these reasons, the distribution of heat energy is not balanced in a global basis.

Since there is unequal receipt of heat energy in the earth, there are heat transfers between places to overcome this problem. They are vertical heat transfers and horizontal heat transfers.

For vertical transfer of heat, they are carried out by long-wave radiation, latent heat transfer and conduction and convection between the earth and the atmosphere. These kinds of process help losing heat to the space, so the earth won’t become warmer and lose its balance.

And for horizontal transfer of heat to be carried out, it is because the amount of radiation received by the earth varies greatly along latitudes and between seasons. There are energy surplus in areas between 40 degrees N and 40 degrees S and energy deficit in areas between 40 degrees N/S and 90 degrees N/S. The equatorial regions are constantly gaining more energy than they lose. While the polar regions are losing energy than they gain. As a result of inequality in energy distribution there is horizontal transfer of heat from areas of surplus to areas of deficit at a global scale. The horizontal transfer of heat is carried out through three ways: sensible heat transfer by warm air masses, latent heat transfer in the form of atmospheric moisture and by ocean currents. The way of sensible heat transfer by warm air masses, it is because of the temperature differences of places, it creates pressure difference and produces horizontal temperature gradients. Then, the wind is blown from high pressure areas to low pressure areas, and the sensible heat is brought from low pressure areas which is warm to high pressure areas which is cool.

For the second way which is latent heat transfer in the form of atmospheric moisture, winds carry water vapour away from the tropics to the polar regions. The water vapour carries energy in the form of latent heat. When the water vapour condenses, this energy is released as heat and warms the surrounding atmosphere.

The last way, the sensible heat is transferred by ocean currents. The ocean transfer significant amount of energy polewards. They carry the warmer water poleward while cold water flows equatorward. These kinds of process help regulate the temperature of different places on the earth.

These vertical and horizontal processes of energy transfer maintain a condition of steady state within the global system, they replenish energy losses in areas where outputs exceed inputs (the higher latitudes) and they remove energy from areas where inputs are in excess. In this way, the energy in the earth-atmosphere system will be more balanced.But with the behaviours of the human beings, the atmospheric balance is affected and influenced greatly.

Firstly, there is the problem of the corruption of the Ozone layer. Ozone is a layer of air in the stratosphere. It can absorb most of the incoming ultraviolet rays of the insolation, such that the living organisms on the earth surface are protected. But during the recent years, because of the massive development of industrial processes and increase of human living standard, there is large amount release of CRCs (chlorofluorocarbons) which will corrupt the ozone layer. This is a serious threat to all the living organisms on the earth surface. Its presence in the upper atmosphere is very important for life on earth. For example, it will increase the amount of Excessive damaging ultra-violet rays which can cause sunburn, skin cancer, and eye cataracts. Longtime exposure may also damage the human immune system.

The corruption of ozone layer in the polar regions is serious because of its shallow layer. And the circulation of air has easily brought the CFCs to the stratosphere at the two poles. And it even creates holes of ozone layer in the polar regions, especially in the Antarctica. According to the Global Environmental Change Report in 2000, the Southern Chile and neighbouring Ushuaia in Argentina are the significantly affected by the Antarctic ozone hole. Ultraviolet radiation levels rose to significant highs after the ozone hole widened to cover the southern tip of South America.

Besides that, there is a more serious problem - Global Warming which is the gradual increase of the temperature of the earth's lower atmosphere as a result of the increase in greenhouse gases. The reason to cause global warming is the burning of fossil fuels like coal that emits carbon dioxide, dust and smoke particles that can trap heat and make the earth warmer. Growth in industry, agriculture, and transportation has produced large quantities of these greenhouse gases which reinforce the blanketing effect. This increase in the quantity of greenhouse gases is trapping more heat and increasing global temperatures. During the past century, atmospheric carbon dioxide has increased from around 280 parts per million (by volume) in 1800 to around 315 in 1958 and 367 in 2000, a 31% increase over 200 years. And the atmospheric temperature has risen 1.1°F (0.6°C), and sea level has risen several inches. There are also longer-term results of global warming include melting of polar ice, with a resulting rise in sea level and coastal flooding; serious changes in agriculture due to climate change; more frequent tropical storms, etc. According to the U.N. Report, it says Africa will be most affected by Global Warming because higher temperatures, heavier rainfall and changes in climate variability would encourage insect carriers of some infectious diseases to multiply and move further afield.

To conclude, the problem of corruption of ozone layer and Global warming, which are mainly caused by man-made activities, have greatly imbalanced the atmospheric energy budget and caused harmful effects. If human beings cannot reduce the activities that can harm the atmosphere, such as the burning of fossil fuels and the usage of CFCs, the balance of the earth-atmosphere system will be severely damaged

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