The Atmosphere

What is the Earth’s Atmosphere?  Our atmosphere is the mixture of gases and particles that surround the Earth.  The atmosphere is held around the Earth by gravity.  Protects us from the sun’s most damaging rays.  Helps maintain the right temperature range for life on Earth.  The oxygen we need to breathe is an important component of the atmosphere.

A Mixture of Gases

Small Particles Floating in the Air  Dust  Volcanic Ash  Sea Salt / Sea Spray  Smoke  Small Pieces of Skin  Pollen  Bacteria

Water in the Atmosphere  Liquid Water (Water droplets forming clouds)  Solid Water (Snow, sleet, hail and ice crystals in clouds)  Water Vapor (Changes into liquid and frozen water creating rain and snow)

How do air pressure and temperature change as altitude increases in the atmosphere?

 Gravity pulls the gas molecules in the atmosphere toward the Earth’s surface causing air pressure.  Air pressure is the measure of the force with which air molecules push on an area of a surface.  Air pressure is measured with a barometer. Atmospheric Pressure

As altitude increases, air pressure and air density decrease.

Temperature Change in the Atmosphere  As altitude increases, temperature changes.  These changes are mainly due to the way solar energy is absorbed in the atmosphere.  Some gases in the atmosphere absorb solar energy while others do not.  Parts of the atmosphere where there are a high percentage of these gases are warmer than the other parts of the atmosphere where these gases are absent.

Pressure and Temperature Change as Altitude Increases This line indicates how temperature changes as altitude increases in the atmosphere. As altitude increases, the atmospheric pressure decreases.

Layers of the Earth’s Atmosphere

The Troposphere 1.The Lowest layer of the atmosphere. We live in this layer. 2.The temperature gets colder as altitude increases. 3.Is the densest layer containing almost 80% of the atmosphere’s total mass. 4.“Weather” occurs in this layer. 5.Almost all of the Earth’s CO 2, water vapor, clouds, air pollution, and life forms are in the troposphere. 6.Clouds in upper part contain ice pellets.

The Stratosphere 1.In this layer, temperature increases with altitude. 2.The Ozone Layer occurs in the stratosphere. 3.Ozone is 3 Oxygen Atoms. (O 3) 4.Absorbs most of the ultraviolet radiation from the sun.

The Mesosphere 1.“Meso” means “middle,” as in middle sphere. 2.Coldest Layer. Temperatures are as low as -120°C at the top of the Mesosphere. 3. Meteoroids begin to burn up in the Mesosphere.

Thermosphere (Divided Into Two Sub Layers) 1.The uppermost layer of the atmosphere. 2.The temperature increases as altitude increases. 3.The temperature in the Thermosphere can reach over 1500°C. 4.The air is thin because the molecules are spread out. 5.No detectable outer limit.

Ionosphere (Lower Part of the Thermosphere) 1.Ions or charged particles in this layer reflect radio signals back to the Earth. 2.The Auroras are occur in the Ionosphere.

Exosphere (Part of the Thermosphere) 1.Outer most layer of the thermosphere. 2.Phone calls and television signals often reach you by way of communication satellites that orbit the Earth in the exosphere.

Scale Model of the Earth’s Atmosphere:

How does the atmosphere protect life on Earth?  By Absorbing or Reflecting Harmful solar radiation.  The Earth’s atmosphere reflects or absorbs most of the radiation from the sun.  The Ozone Layer absorbs most of the radiation from the sun.  By maintaining the Right Temperature Range for living things.  The “greenhouse effect” is the process by which gases in the atmosphere, such as water vapor and carbon dioxide, trap the sun’s heat escaping from the Earth’s surface.  Unfortunately, the burning of fossil fuels adds too much CO 2 and many scientists believe is causing global warming.