Importance of Earth’s Atmosphere
1. The atmosphere is a thin layer of gases surrounding the Earth
2. It is hundreds of kilometers high but relative to Earth’s size it is like the skin on an apple
3. The atmosphere contains the oxygen, carbon dioxide, and water needed for life on
Earth
4. It also acts as insulation on a house
5. The atmosphere protects organisms on Earth
a. Meteors will burn up before reaching the surface
b. It protects us from the Sun’s harmful rays
WHAT DOES THE ATMOSPHERE DO FOR LIVING THINGS ON EARTH?
Origins of Earth’s Atmosphere
1. Earth was a ball of molten rock in space when it first formed
2. Earth cooled slowly and its surface solidified
3. Volcanos erupting on the surface spewed out gases that surrounded the Earth and
formed the atmosphere
4. The earliest atmosphere is thought to be water vapor, or water gas, and did not have
enough oxygen to support life
5. Water vapor fell as rain as the Earth continued to cool
6. Eventually enough water accumulated to form oceans.
7. Most CO2 in the original atmosphere is in rocks at the bottom of Earth’s oceans
HOW DID THE EARTH’S PRESENT ATMOSPHERE FORM?
Composition of the Atmosphere
1. Today’s atmosphere mostly contains gases, including nitrogen, oxygen, and carbon
dioxide. There are also liquid and solid particles in the air.
a. Nitrogen = 78%
b. Oxygen = 21%
c. Other gases (vapor, argon, C02) = 1%
i. Ozone is present in very high altitudes as well as heavy urban areas on
Earth
2. Tiny solids like dust, salt, and pollen can be found in the atmosphere as well
3. Water droplets are the most common liquid in the atmosphere
4. There are also trace amounts of acids from fossil fuels being burned
WHAT IS EARTH’S ATMOSPHERE MADE OF?
Layers of the Atmosphere
1. The atmosphere has 5 layers
a. Troposphere
i. Layer closest to the earth’s surface
ii. 8-15 km above surface
iii. Warmest part is closest to earth because the surface warms up then
radiates back into the air
b. Stratosphere
i. Above the troposphere
ii. 15-50 km above surface
iii. Ozone layer is located here
iv. Temps increase the higher you go in the stratosphere due to higher
concentration of ozone
1. Ozone (O3) absorbs heat more efficiently than oxygen (O2)
2. It protects us from harmful rays that could cause cancer
c. Mesosphere and Thermosphere
i. 50 – 85 km for mesosphere, 85 – 500 km max for thermosphere
ii. Only 1% of the atmosphere’s gas are found in these layers
iii. Meteors burn up in these layers
iv. Contains the Ionosphere – auroras
1. Ions from the Sun strike air molecules causing colors
v. Exosphere
1. Outermost layer of the atmosphere
2. No defined “edge”
3. Air density is so low that molecules rarely strike each other
WHAT ARE THE LAYERS OF THE ATMOSPHERE?
Air Pressure and Altitude
1. Gravity pulls the atmosphere towards the Earth
2. Air Pressure – the force a column of air will exert on anything
3. As altitude increases, air pressure decreases
Temperature and Altitude
1. In the troposphere and mesosphere, as altitude increases, temperature decreases.
2. In the stratosphere, temperatures increase with altitude due to ozone
3. In the thermosphere, the temperature increases with altitude due to these areas getting
large amounts of radiation and energy from the sun
Energy from the Sun
1. The energy from the Sun takes 8 minutes to travel 148 km to Earth
2. The Sun’s energy gets to Earth through radiation – the transfer of energy by
electromagnetic waves
3. The Sun’s rays = 99% visible light, UV, and infrared
4. Visible like is light you can see
a. Converted into thermal energy
5. UV and infrared radiation are just out of visible range of wavelengths
a. UV can burn skin and cause skin cancer in high amounts
b. IR is sensible as thermal energy/warmth
WHAT IS THE DIFFERENCE BETWEEN VISIBLE AND UV LIGHT?
Energy on Earth
1. When energy from the Sun reaches Earth, some of it is absorbed, and some of it is
reflected into space.
2. 20% of the energy is absorbed by oxygen, ozone, and water vapor as UV.
3. Some is absorbed as IR by water and CO2
4. Visible light must be converted to thermal energy before it can be absorbed
5. Bright surfaces like clouds or ice will reflect about 30% of the Sun’s radiation
6. 50% of solar radiation is absorbed by the surface of the Earth
7. There is a balance between the incoming radiation from the Sun and outgoing radiation
from Earth
Greenhouse Effect
1. The glass of a greenhouse will allow light to pass through and then gets converted into
thermal energy (IR)
2. The glass will prevent the IR from escaping and it warms the greenhouse
3. Gases in the atmosphere act like the glass on a greenhouse, keeping some heat close
a. Water vapor (H2O), Carbon dioxide (CO2), and Methane (CH4)
Thermal Energy Transfer
1. Conduction
a. The transfer of heat through contact
b. Examples: Mug of coffee heating up a spoon, touching the radiator with your
hand
c. Conduction occurs where the atmosphere touches Earth
2. Convection
a. Transfer of heat by movement of particles within matter
b. Examples: boiling water, hot air balloons
c. Convection occurs where hot air
3. Latent Heat
a. Latent heat is exchanged when water changes from one phase to another.
b. Latent heat will transfer heat from the surface of the Earth to the atmosphere.
Circulating Air
1. Heat is transferred through the atmosphere through convection
2. Air that is heated will rise
3. Cooler, denser air pushed hot air out of the way
4. Air is always moving and affects climate and weather around the world
Stability
1.