Energy & The Atmosphere
Image courtesy of geoengineering.global
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Energy Entering the Atmosphere
Electromagnetic radiation from the Sun is always bombarding the Earth. The Sun produces all 7 forms of EM radiation, as seen in the diagram to the left. Each one of these types of radiation have differing penetrating abilities into the atmosphere. Some get all the way to the Earth's surface, while others are absorbed or reflected as they come into the atmosphere. The image below gives a good overview of the different forms of light's penetrating ability. |
As you can see, the high energy gamma, x-ray and most of the UV rays are stopped by the ozone layer. A lot of the infrared and microwave radiation also does not penetrate the atmosphere. However, all of the radio, some low energy microwave, some high energy IR, all the visible light and the low energy UV (known as UV-A) do reach the Earth's surface. Essentially, the Earth's atmosphere let's in all the light we need to see, warm and some other less harmful energies. And it absorbs or reflects all the damaging light. It's actually pretty remarkable.
Greenhouse Effect
Greenhouse gases include H2O, CO2, CH4, and other gases. These gases, present in the atmosphere, allow solar radiation (sun rays), radiation on the electromagnetic spectrum, to enter the Earth’s atmosphere. When the radiation reflects off of the surface of the Earth, the radiation loses some of it energy. Some of this radiation has enough energy to escape the atmosphere, but some does not. The greenhouse gases trap this lower energy infrared radiation in the atmosphere, which then warms the surface.
The greenhouse effect has gotten a bad rap recently. It has been blamed for global warming. In reality, life as we know it would die without the greenhouse effect. The greenhouse gases trap heat during the day. This heat is then slowly released at night. Since it is retained at night, temperatures remain warm at night. Without these gases, there would be a larger swing in temperatures at night.
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For example, in the desert, there is less water. During the day, the temperature gets extremely hot, due to the direct sunlight. But, there is very little water, or other greenhouse gases, and not much of that heat is retained. At night, in the desert, if can often go below freezing. If this were to happen all over the world, the plants that we grow will freeze at night, and we will not be able to grow crops. Greenhouse gases provide the stored heat we need to continue life as we know it.
Global Warming
Global Warming
Global warming is the trend of the average surface temperature of the earth increasing. Global warming is a theory that suggests that the increase of greenhouse gases in the atmosphere has caused the overall global temperature to rise. Is there evidence that global warming is occurring? The largest piece of evidence is the increase of average global temp. of 1 OF in the past 100 years. This average of 1OF is not consistent over the whole planet. For instance, the average temperature at the poles has increased about 2 - 5 OF, where the average temperature at the equator has not really increased.