THE EARTH’S ATMOSPHERE: Atmospheric Layers SOL 6.6

These layers are the… troposphere, the stratosphere, the mesosphere, and the thermosphere.

Let’s find out where these layers are located in relation to the Earth’s surface and how they are affected by temperature.

Troposphere The troposphere is the lowest layer of the atmosphere that lies next to the Earth’s surface.

Troposphere Most of the air that makes up the atmosphere is found in the troposphere.

Troposphere It extends to about 14 kilometers (around 9 miles) above the Earth and is where virtually all weather takes place.

Troposphere As you move up into the troposphere the temperature decreases. At the top of this layer the air temperature is about - 60°C (-76° F).

Stratosphere The stratosphere begins at the top of the troposphere (14 km/ 9 miles) and extends to about 50 kilometers (31 miles) above the surface of the Earth.

Stratosphere As you move up into the stratosphere the air temperature actually increases.

Stratosphere This occurs because of ozone. Ozone is a gas that absorbs solar radiation and releases it as heat. The stratospheric or "good" ozone protects life on Earth from the sun's harmful ultraviolet (UV) rays.

Stratosphere The ozone layer/ ozonosphere is located at the bottom of the stratosphere.

Mesosphere The mesosphere begins at about 50 kilometers (31 miles) above the Earth’s surface and extends to 80 kilometers (50 miles).

Mesosphere As you move up into the mesosphere, the air temperature decreases. Temperatures at the top of this layer can drop to -90°C (- 130°F ).

Mesosphere Interestingly, this layer also protects the Earth. Meteoroids entering Earth’s atmosphere usually burn up in the mesosphere.

Thermosphere The thermosphere is the outermost layer of the Earth’s atmosphere.

Thermosphere It begins at 80 km (50 miles) above the Earth and extends outward into space. Sometimes the thermosphere and exosphere are listed as separate layers.

Thermosphere The higher you move in this layer, the higher the temperature. Temperatures in the thermosphere can reach 1,800°C (3,300°F)!

Thermosphere The beautiful colors of the aurora borealis or northern lights occur in this atmospheric layer.

Thermosphere This is also where the space shuttle orbits the Earth!

Thermosphere

Thermosphere The ionosphere is found at the bottom of the thermosphere (close to the mesosphere). The exosphere is located at the top of the thermosphere.

1)   Troposphere 1) Troposphere a) This is the layer that touches the Earth (we live in) b) The temperature decreases 6.5°C every kilometer you go up. It stops rising at 12 km. c) The altitude of the troposphere is from 0 km to 12-17 km. d) Two features are: i) Almost all weather exists here ii) Convection currents carry streams of warm air upward

2)   Stratosphere a) The temperature of the lower stratosphere remains a constant -60°C b) The temperature of the upper stratosphere rises to +18°C, because of the hot ozone layer. c) The altitude of the stratosphere is from 17-50 km. d) Two features are: i) Jet streams – horizontal movement of air-very strong winds. ii) Ozone Layer – Protective layer of earth – holds in heat and protects from UV rays. Ozone smells clean and sharp – Ozone is released during lightening. e) The stratosphere contains the most oxygen in the atmosphere.

3)   Mesosphere a) The temperature of the Mesosphere decreases to -100°C. b) It is the coldest region of the atmosphere. c) The altitude of the mesosphere is from 50-80 km. d) The feature of this region is that it protects Earth from meteors by burning them up before they hit Earth. The heat is caused by friction as they travel through this layer.

4)   Thermosphere a) The temperature of the thermosphere is +2000°C. So hot it can’t be registered on a thermometer. (It is hot because it is exposed to constant UV radiation from the Sun. b) It is the hottest region of the atmosphere. c) It is broken into two smaller regions: Ionosphere and Exosphere

i) Ionosphere (1) The altitude of the ionosphere is from 80-550 km i) Ionosphere (1) The altitude of the ionosphere is from 80-550 km. (2) Ions are present here (charged particles) (3) Responsible for radio communication ii) Exosphere (1) The altitude of the exosphere is from 550-3200 km. (2) Air so thin there is great visibility. (3) Satellites orbit there – to transmit television and telephone communication.