Earth's Changing Atmosphere
1.1 Earth's atmosphere supports life
The atmosphere is the whole layer of air that surrounds the earth. The atmosphere supports life and protects it. The gases of the atmosphere keep earth warm and transport energy to different regions of the planet. Without the atmosphere, the oceans would not exist, life would not survive, and the planet would be a cold, lifeless rock.
The atmosphere is the whole layer of air that surrounds the earth. The atmosphere supports life and protects it. The gases of the atmosphere keep earth warm and transport energy to different regions of the planet. Without the atmosphere, the oceans would not exist, life would not survive, and the planet would be a cold, lifeless rock.
The atmosphere is extremely thin.
Characteristics of the atmosphere:
Altitude: Is the distance above sea level. The higher you go above sea level, the thinner the air gets.
Density: Is the measurement of the thickness or thinness of air. Density is the amount of mass in a given volume of a substance. If two objects take up the same amount of space, then the object with more mass has a greater density than the one with less mass. For example, a bowling ball has a higher density than a soccer ball.
Altitude: Is the distance above sea level. The higher you go above sea level, the thinner the air gets.
Density: Is the measurement of the thickness or thinness of air. Density is the amount of mass in a given volume of a substance. If two objects take up the same amount of space, then the object with more mass has a greater density than the one with less mass. For example, a bowling ball has a higher density than a soccer ball.
Natural processes modify the atmosphere.
Water Cycle:
- water from oceans and lakes changes into gas and enters the atmosphere
- plants release water vapor from their leaves
- rain falls from the sky
- Animals inhale oxygen and exhale carbon dioxide
- Plants take in carbon dioxide and release oxygen
- Plant and animals use solids and liquids that contain nitrogen and then the nitrogen returns to the soil when the organisms die.
- The soil releases nitrogen back into the air as nitrogen gas
Sudden changes modify the atmosphere
How do these three events change the atmosphere?
1.2 The Sun supplies the atmosphere's energy
Two main things happen to sunlight that reaches the Earth. Some is reflected and some is absorbed. The light that you can see is one type of radiation. Radiation is energy that travels across distances in the form of certain types of waves. Visible light and other types of radiation can be absorbed or reflected.
70 % of solar radiation that reaches the Earth is absorbed. Most of this energy is absorbed by oceans, land forms, and living things. Think about walking on hot sand. The sand has absorbed the solar energy from the sun. Your body may be comfortably warm, except for the burning-hot soles of your feet. The sand is much warmer than the air because sand absorbs solar energy all day and stores it in one place. The air also absorbs solar energy but moves it around and spreads it out.
The atmosphere moves energy.
Radiation, conduction and convection are processes that move energy from place to place.
Back to the sand...First, radiation from the sun warms the sand. Second, the hot sand conducts energy to the air. Third, the warm air carries energy upward in convection.
This constant motion caused by radiation from the sun is what causes our atmosphere to continually change. Differences in density produce the motion of air convection. Warm air has more energy, so the molecules move faster than they do in cool air. The motion make the molecules collide more, so they stay farther apart. Cool, dense air is heavier, so it tend to sink and push warm, less dense air upward.
The atmosphere has temperature layers.
Troposphere:
Troposphere:
- nearest earth's surface
- convection turn air over
- 80% of total mass of atmosphere
- warmed from below by the ground
- temperature is highest at ground level and decreases as you go up
- ozone layer located here (absorb solar radiation)
- temperature increases as you rise
- air is extremely thin meteors enter the atmosphere here and burn up
- it is heated from below so the temperature decreases as you rise
- last layer before outer space
- very hot because the molecules absorb solar radiation
- temperature increases as you rise