The atmosphere is a blanket of gases that extends from the surface of the Earth and reaches over 560 kilometers (348 miles)

The troposphere is the lowest region of the Earth's atmosphere, where masses of air are very well mixed together and the temperature generally decreases with altitude. Most weather on Earth occurs within the troposphere, because this is where the water vapor is. General Altitude of the troposphere is from km. Occasionally, a temperature inversion occurs, and the temperatures actually increase with altitude within this zone.

In the stratosphere, the air is stable and less turbulent. The temperature of the air within the stratosphere increases with altitude. This increase in temperature with altitude is due to the presence of stratospheric OZONE near an altitude of 25 km. Ozone molecules absorb high-energy ultraviolet rays from the sun, which warm the atmosphere at that level. The stratosphere extends to 50 km.

In the Earth's mesosphere, the air masses are relatively mixed together and the temperature decreases with altitude. This is also the layer in which a lot of meteors burn up while entering the Earth's atmosphere. The mesosphere extends from the top of the stratosphere (50 km) to an altitude of about 90 kilometers, and can be detected by looking at the limb. Limb

When the Sun is active, temperatures within this zone can reach up to 1,500 °C, or higher! The thermosphere can extend above the Earth’s surface as far as 480 km. The thermosphere also includes the region of the Earth's atmosphere called the ionosphere. When a rapidly moving particle, such as an electron, collides with a gas atom, an electron is ejected from the atom, leaving a positively charged ion. Ionization processes release energy, which heats up the upper atmosphere. Temperature, therefore, increases with altitude in the ionosphere and it is extremely hot compared to surface temperatures.

Even thought the ionosphere represents less than 0.1% of the total mass of the Earth's atmosphere, it is extremely important. The space shuttle flies in this area of the atmosphere, and this is also where the aurora borealis is found. Auroras are wispy curtains of light caused when the sun strikes gases in the atmosphere above the Polar regions. Different regions of the ionosphere make long distance radio communication possible by reflecting the radio waves back to Earth.

The region of our atmosphere where atoms and molecules escape Earth’s gravitation and move into space is referred to as the exosphere. This is truly the upper limits of Earth’s atmosphere, and some of our satellites are stationed in this area. It is 500 to 1000 km above the Earth’s surface A region within and beyond the exosphere is known as the magnetosphere. It is not truly a layer of Earth’s atmosphere so it is not bound by gravitation, but by magnetism.

Ultra Violet (UV) Radio waves Infrared waves (IR) Visible light (ROYGBIV) Microwaves X-Rays Gamma Rays When learning about the Greenhouse Effect, it is important to understand the electromagnetic spectrum, and the lengths of waves within it. In order, from longest to shortest wavelengths, the spectrum is as follows:

Sunlight travels through space in a very short and powerful wavelength, known as Ultra violet (UV). Some UV radiation is reflected or absorbed by the ozone (O 3 ) molecules located in our stratosphere However, it can be detected by our skin when we get a sunburn, or feel warmed by the sun. This UV light is not seen by our eyes (as only visible light is within the spectrum our eyes can detect).

Some UV radiation as well as visible light is able to penetrate the atmosphere and hit the Earth’s surface. Some of that UV radiation and visible light which reaches the surface is absorbed by vegetation, soil, water, and rock. As you may remember, it is this heating of the water over our tropical oceans that drives much of the climate on our planet. Which Earth surfaces do you think are responsible for the greatest absorption?

Albedo is the reflection coefficient, or the reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it. Albedo is measured on a scale from zero for no reflecting power of a perfectly black surface, to 1 for perfect reflection of a white surface. Typical albedo ranges from 0.9 for fresh snow, to about 0.04 for charcoal

Some of that radiation (which is absorbed) is converted, and re-radiated back into Earth’s troposphere as long wave, less powerful radiation known as Infra-red This long wave Infrared radiation (IR) is unable to penetrate the Earth’s greenhouse gas layer, and becomes trapped, as heat energy near the surface in our atmosphere The IR radiation (just like the UV) is not seen by our eyes, but it can be felt as warmth on our skin. Many scientists believe it is this effect that is causing the global rise in temperatures known as Global Warming.

Global Warming was first recognized by Svante August Arrhenius in His meteorological studies made him conclude that the weather patterns had changed in Sweden since the beginning of the industrial revolution (1800). He proposed that burning of fuels was causing these changes.  80% of the Earth's increase in temperature is due to the burning of fossil fuels like coal and oil and the resulting CO 2 emissions. The industrial revolution has been fueled by coal and oil.  The other 20% occurs naturally and comes from decomposing vegetation. He was correct of course in that burning fossil fuels indeed had contributed to global warming.

 CO 2 (carbon dioxide): 25% increase in last 200 years.  CFCs (chlorofluorocarbons): used as solvents to clean computer chips and keep the cool (a.k.a. Freon) in air conditioners. One CFC molecule can absorb 20,000 times more infrared energy than CO 2 molecules.  CH 4 (methane): increasing 11% per year. One CH 4 molecule can absorb 25x the IR as CO 2 molecules (caused by burning of biomass, and livestock emissions)  NO x (nitrous oxides): accelerated by the use of nitrogen-based fertilizers. Absorbs 250x more IR than CO 2  O 3 (ozone): very minor influence  H 2 O (water vapor): not caused by humans Current estimates indicate that CO 2 is responsible for about one half the problem. CH 4 and NOx each contribute one fourth.

As ominous as this all sounds, this greenhouse effect is vital to life on Earth. With no atmosphere on the moon: (no atmosphere means no greenhouse effect) In the illuminated half, the temperatures often reach 216° F In the dark half, the temperatures often plummet to -243° F Without greenhouse effect on Earth, the average temperature would be -27° F Loss of rainforests that take in carbon dioxide, and the burning of fossil fuels by cars, factories and plants which release carbon dioxide are part of the causes. The one greenhouse gas that has truly been increasing in the past 50 years is carbon dioxide.