Interactions In The Atmosphere

Something happens between the top of the atmosphere and the surface of the Earth. Something sucks energy (interacts with it) out of the energy sent by the Sun. The ozone layer is a layer of the atmosphere that is about 25 kilometers above the surface of the Earth. Its main function is to absorb UV light from the incoming energy of the Sun. Ozone (O3) is actually three oxygen atoms bonded together.

When a UV ray hits the ozone molecule, it breaks apart. You then have one O2 molecule and one oxygen atom. The oxygen atom is recycled in the ozone layer because there is always more ozone being created. Not all of the ultra-violet light is removed, only about 60% of it.

Disappearing Ozone

You may have heard scientists talking about the ozone layer shrinking. They used satellites and found an area over Antarctica where there is actually a big hole. They think it's because of chemicals from man's industrial manufacturing. Others say the layer may grow and shrink naturally.

If the ozone layer disappears, almost double the amount of UV light will get to the surface of the Earth. That extra amount of radiation could cause mutations in DNA that cause cancer and mutated plants and animals. There is also a lot of water and carbon dioxide in the atmosphere. As the water vapor and gases float in the atmosphere, they interact with the incoming light. Scientists have shown that they absorb infrared (IR) light waves.

Types of Scattering

The atmosphere also interacts with incoming radiation through a process called molecular scattering. Light rays are very small. Huge numbers of small molecules float in the atmosphere. As the light comes from the Sun, these small molecules scatter the light. Scientists call it Rayleigh scattering. The amount of scattering increases as the wavelength gets shorter. So IR light is scattered less than UV (IR has a longer wavelength).

Particle scattering is a process that involves small pieces of matter that are much larger than individual molecules. There are all sorts of particles in the atmosphere. Good examples are smog and dust. Think about all of the dust that goes into the atmosphere when a volcano explodes. All of those particles affect the amounts of incoming energy. Increased numbers of particles usually decrease the amount of light that hits the Earth.

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