THE ATMOSPHERE = a thin layer of gas that protects the Earth’s surface from extreme temperatures and solar radiation.

We often refer to the atmosphere as “air.” We can’t see it, smell it, or taste it but air is actually made up of molecules of many different gases and tiny particles of solid matter. We can sure feel it when it moves though!

Importance of the Atmosphere * Without the atmosphere, Earth would look a lot more like the Moon. * Atmospheric gases, especially carbon dioxide (CO2) and oxygen (O2), are extremely important for living organisms.

Earth’s Moderate Temperature The atmosphere helps block harmful UV radiation from the sun AND helps to trap heat on Earth. Without an atmosphere, the Earth would be frigid at night and scorching during the day.

Water Vapor Humidity is the amount of water vapor in the air, and varies place to place. Zebulon, NC vs. Flagstaff, Arizona Water vapor can be up to 4% of the atmosphere.

Water Vapor Warm air holds more water vapor than cold air, which is why it is more humid in the summer than the winter.

The atmosphere stores a lot of water for the water cycle. The water cycle describes the journey of water from the atmosphere to land and back again. The atmosphere stores a lot of water for the water cycle.

Gases of the Atmosphere What do you think is the most abundant gas in the atmosphere? Nitrogen: 78% (important for plant growth & as a chemical ingredient for living things) Oxygen: 21% Argon: 0.93% Carbon dioxide: 0.04%

PHOTOSYNTHESIS 6CO2 + 6H2O + light  C6H12O6 + 6O2 Plants use CO2 and create O2. Responsible for nearly all the oxygen in the atmosphere.

RESPIRATION C6H12O6 + 6O2  6CO2 + 6H2O + energy Animals then use oxygen to convert sugar into food energy they can use.

The Ozone Layer Ozone (O3) is a gas that makes life on Earth possible by absorbing high-energy ultraviolet (UV) radiation coming from the Sun. Pollutants called chlorofluorocarbons (CFCs) are destroying the ozone. CFCs are used in refrigerators, air conditioners, aerosol sprays, and foam packaging ~ if products leak, CFCs enter atmosphere Ozone layers has a large hole over Antarctica and a smaller one over the North Pole

The Greenhouse Effect Some of the Sun’s energy coming through Earth’s atmosphere is reflected or absorbed by gases and/or clouds in the atmosphere. Solar energy that is absorbed by the Earth’s land and water is changed to heat that moves/radiates back into the atmosphere (troposphere) where gases absorb the heat, a process known as the greenhouse effect.

The Greenhouse Effect

CFCs and other man-made compounds are also greenhouse gases. Human activities may increase the amount of greenhouse gases in the atmosphere.

Particles in the Atmosphere * Dust, soil, salt, smoke, or ash. * Particulates (tiny particles) are needed for water to condense on to form clouds. *Too many particulates can pollute the air.

Sound Waves! The atmosphere is made of gases that take up space and transmit energy, like sound waves. No atmosphere = NO SOUND (Explosions in space are silent!)

The atmosphere has 5 layers: Different elevations Different properties, such as air pressure, density, water vapor, and temperature. 90% of the gas is in the troposphere.