1. Earth’s Changing Atmosphere
Earth’s Atmosphere Supports Life
Lesson 2

2. ATMOSPHERE BIOGRAPHY VIDEO

3. The atmosphere makes life on Earth possible
The atmosphere is a whole layer of air that surrounds Earth which supports and protects life in several ways:
Absorbs harmful radiation
Maintains Earth’s temperatures
Provides elements essential for life

4. Characteristics of the Atmosphere
The atmosphere has chemical and physical properties
The density of the atmosphere decreases with altitude
Altitude is the distance above sea level
Density is the amount of mass in a given volume of a substance (the thickness or thinness of air)
The decrease of density with greater altitude means that most of the mass of the atmosphere is close to Earth’s surface

5. Materials in the Atmosphere
Most of the materials in the atmosphere are gases (Nitrogen 78%; oxygen gas 21%; Argon, carbon dioxide and other gases 1%)
Nitrogen: promotes plant growth
Oxygen: needed for animals & plants to perform life processes
Carbon dioxide: plants use it to make food
Other tiny particles of solid or liquid materials include: dust, sea salt, and water droplets exist in the atmosphere

6. Nitrogen gas is the major component of the atmosphere
Carbon dioxide plays a large role in global warming (burning of fossil fuels)
Ozone gas only makes up a small layer of the atmosphere and protects the surface of the Earth from excessive UV radiation.

8. Atmosphere Fact Sheet Layers Troposphere Stratosphere Mesosphere
Temp. Range Location Width (in miles) Inside Layer Other Fact
Layers
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

9. Earth is heated unevenly by the Sun
At the poles, the Sun’s rays strike the Earth’s surface at a much greater angle (less heat and energy are absorbed)