What is the Earth’s atmosphere?
A layer of gases held by gravity
The atmosphere plays a crucial role in protecting life on Earth.
What are the functions of the atmosphere?
- Absorbs harmful UV radiation
- Regulates Earth’s temperature (greenhouse effect)
- Reduces temperature differences between day and night
What is the composition of dry air by volume?
- 78.09% nitrogen
- 20.95% oxygen
- 0.93% argon
- 0.039% carbon dioxide
- ~1% water vapor (variable)
What is the total atmospheric mass?
~5 x 10^18 kg
This mass is primarily concentrated within the first 11 km of the atmosphere.
What is the Karman Line?
Considered the boundary with outer space, located at ~100 km
What is the Exosphere?
Outermost layer of the atmosphere, above ~600 km, mostly hydrogen and helium
What is the Thermosphere?
Extends from ~80 km to 600-800 km, very high temperatures (up to 1500°C)
What occurs in the Mesosphere?
Coldest layer of the atmosphere, located from 50 to ~85 km, meteors burn up here
What is the Stratosphere known for?
Contains the ozone layer and temperature increases with height, located from 12 to ~50 km
What is the Troposphere?
Layer from surface to 9–17 km where most weather occurs and temperature decreases with altitude
What is the Ozone Layer?
Found in the lower stratosphere, located at 15–35 km
What is the Ionosphere?
Layer from 50–1000 km, ionized by solar radiation, affects radio signals
What is the difference between Homosphere and Heterosphere?
Homosphere is the lower atmosphere (up to ~100 km) where gases are well mixed; Heterosphere is above ~100 km where gases separate by weight
What does temperature measure?
The average speed (kinetic energy) of air molecules
What are the three temperature scales?
- Kelvin: starts at absolute zero (-273°C)
- Celsius: 0°C = freezing, 100°C = boiling
- Fahrenheit: 32°F = freezing, 212°F = boiling
Fill in the blank: Specific heat is the energy needed to raise 1g of substance by _______°C.
1
What is latent heat?
Heat used to change state (e.g., ice to water)
What are the methods of heat transfer?
- Conduction: Heat transfer by direct contact
- Convection: Heat transfer by fluid motion
What is a mercury barometer?
Device that measures atmospheric pressure by balancing a mercury column
What is normal atmospheric pressure in millibars?
≈ 1013 mb/hPa
What is Relative Humidity (RH)?
Actual / Maximum vapor × 100%
What is the Dew-point?
Temperature at which air becomes saturated
What is fog?
A cloud on the ground, reducing visibility < 1 km
What are the main types of fog?
- Radiation fog
- Advection fog
- Mixing fog
- Sea smoke
