Our planet is surrounded by layers of atmosphere

Our planet is surrounded by layers of atmosphere. These layers differ in composition density temperature pressure The differences within these layers allow life on earth to exist.

The atmosphere at the surface of the earth is very different from the atmosphere just a few kilometers up. How do you think these layers work together to maintain our current living conditions here on earth?

The layers of atmosphere act like a blanket to protect and insulate the earth. The layers are clearly visible from outer space.

Thickness • The atmosphere is a very thin (relatively) layer of gas over the surface of the Earth • Earth’s radius ~ 6400 km • Atmospheric thickness ~ 100 km • (If you travel 100 km from Mc. Kinney you will only be in Ft Worth. If you do it vertically you’d be in space!)

As you move away from the earth’s surface, the temperature will initially drop. The air pressure will continue to decrease the higher you go.

We will begin at the surface of the earth and work our way into the outer limits of Earth’s atmosphere.

The layer closest to the earth is the troposphere. This layer is approximately 10 km thick. All life exists within this layer. Due to rising and falling currents of air, all weather takes place within this layer.

Temperatures increase as you enter the stratosphere. This is due to the ozone layer present at the upper edge of the layer. The stratosphere reaches 50 km above the earth. ozone Stratosphere 10 -50 km Troposphere 10 km

The ozone layer is a highly reactive form of oxygen that absorbs ultraviolet light. This layer acts like an insulator to protect the earth from harmful rays. It also keeps too much heat from escaping into the outer atmosphere. ozone Stratosphere 10 -50 km Troposphere 10 km

“Meso” means middle; hence, this is the middle layer of our atmosphere. The temperature of this layer drops from comfortable 00 C. to a chilling -800 C ! Most meteors burn up in this layer. 50 -80 km Mesosphere ozone Stratosphere Troposphere 10 -50 km 10 km

Temperatures in this layer increase from 80°C to a hot, 800°C. The space shuttle orbits the earth in this layer. 80 -500 km Thermosphere 50 -80 km Mesosphere ozone Stratosphere Troposphere 10 -50 km 10 km

The Ionosphere is located in the upper Thermosphere. 150 -500 km Thermosphere Ionosphere 50 -80 km Mesosphere ozone Stratosphere Troposphere 80 -500 km 10 -50 km 10 km

Temperatures increase as we enter this layer. The atmosphere is very thin and becomes electrically charged; hence, the name ionosphere. This layer also absorbs photons (light particles) from the sun. 150 -500 km Thermosphere Ionosphere 50 -80 km Mesosphere ozone Stratosphere Troposphere 80 -500 km 10 -50 km 10 km

This ionization causes a natural phenomena called the Aurora Borealis. Thermosphere 150 -500 km Ionosphere 50 -80 km Mesosphere ozone Stratosphere Troposphere 80 -500 km 10 -50 km 10 km

Exosphere The Exosphere is the outermost layer. 500 - 800 km 150 -500 km Thermosphere Ionosphere 50 -80 km Mesosphere ozone Stratosphere Troposphere 80 -500 km 10 -50 km 10 km

Exosphere The temperature ranges from 800° to 2000°C in the Exosphere. 150 -500 500 - 800 km km Thermosphere Ionosphere 50 -80 km Mesosphere ozone Stratosphere Troposphere 80 -500 km 10 -50 km 10 km

Exosphere Molecules of gas are about 2 km apart in the Exosphere. 500 - 800 km 150 -500 km Thermosphere Ionosphere 50 -80 km Mesosphere ozone Stratosphere Troposphere 80 -500 km 10 -50 km 10 km

Exosphere Satellites orbiting Earth are found in the Exosphere. 500 - 800 km 150 -500 km Thermosphere Ionosphere 50 -80 km Mesosphere ozone Stratosphere Troposphere 80 -500 km 10 -50 km 10 km

The atmosphere is composed of a variety of gases: • Nitrogen 78% • Oxygen 20. 9% • Argon 0. 9% • Carbon Dioxide 0. 035% • Trace amounts of Helium, Neon, Methane and Krypton

The composition of the atmosphere remains the same throughout, the layers just vary in density. All of life is dependent on the delicate balance of the gases found in Earth’s atmosphere. What do you think would happen if there was a sudden increase or decrease in a certain atmospheric gas? Is it happening now? Give examples.

Air Density and height

Pressure and Density Decrease with Height

Low Pressure Low Density High Pressure High Density