Name: ______Date: ______

**COMPOSITION OF THE ATMOSPHERE**

- Earth has FOUR main systems that interact: atmosphere, hydrosphere, biosphere, and geosphere.

- The atmosphere is the layer of gas that surrounds the earth more commonly known as “air”.

- The atmosphere has different properties at different elevations and locations throughout the world, including air pressure, temperature, and water vapor.

- The atmosphere has five layers, including the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.

  • Each layer is at different elevations.
  • 90 % of the gas is in the lowest layer, the troposphere.

- We can’t see, smell, or taste the gases of the atmosphere, but air is actually made up of molecules of many different gases and tiny particles of solid matter.

- NITROGENT is the most abundant gas in the atmosphere.

  • Nitrogen: 78%
  • Oxygen: 21%
  • Argon: 0.93%
  • Carbon dioxide: 0.04%

-HUMIDITY is the amount of water vapor in the air, and varies place to place.

  • Water vapor can be up to 4% of the atmosphere.
  • Circle which has more water vapor/humidity: Flagstaff, Arizona or Zebulon, NC?

-GREENHOUSE GASES trap heat in the atmosphere so that Earth has a moderate temperature.

  • Natural greenhouse gases include: carbon dioxide, ozone, water vapor, and methane.
  • CFCs and other man-made compounds are also greenhouse gases.
  • Human activities may increase the amount of greenhouse gases in the atmosphere.

- PARTICULATES (tiny particles) in the atmosphere include: dirt, dust, pollen, or salt.

  • Some particulates pollute the air.
  • Particulates are needed for water to condense on. Without particles, water vapor could not condense, clouds could not form, and we WOULD NOT HAVE RAIN!!
  • Where does the dust come from?
  • Where does the ash come from?
  • Where does the salt come from?
  • Where does the soil come from?

**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.

PHOTOSYNTHESIS: plants use carbon dioxide and create oxygen.

  • Responsible for nearly all the oxygen in the atmosphere!

6CO2 + 6H2O + light energy  C6H12O6 + 6O2

Carbon dioxide + water + light energyGlucose (sugar) + oxygen

RESPIRATION: animals then use oxygen to convert sugar into food energy they can use.

C6H12O6 + 6O2  6CO2 + 6H2O + useable energy

Glucose (sugar) + oxygen carbon dioxide + water + energy

NITROGEN CYCLE: Nitrogen promotes growth and is an important ingredient in the chemicals that make up living things.

WATER CYCLE: Water spends a lot of time in the atmosphere. The atmosphere is an important reservoir for water.

- OZONE (O3) makes life on Earth possible by absorbing high-energy ultraviolet (UV) radiation from the Sun.

  • Protects living things on Earth’s surface from the Sun’s most harmful rays.
  • Highest concentration of ozone is in the second (Stratosphere) layer of the atmosphere.

- The atmosphere helps keep Earth a moderate temperature. Without an atmosphere, the Earth would be frigid at night and scorching hot during the day.

  • GREENHOUSE GAS EFFECT (see notes above)

- 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! How weird is that?!!!