Atmospheric Circulation Flashcards
What factor is the energy of the sun?
An external factor
What are the 5 components impacted by the suns energy?
- Atmosphere
- Land surface
- Hydrosphere
- Biosphere
- Cryosphere
Outline the global climate in 2018
- 4th hottest year on record
- Linked to climate change - atmosphere and surface of ocean regulate climate
- US and Caribbean has 2 major hurricanes
- Extreme air temp in Japan and Australia
Outline the structure of the earths atmosphere
- 78% nitrogen
- 21% oxygen
- 0.09% argon
- 0.04% carbon dioxide
What are the different layers of the atmosphere?
- Troposphere - where weather occurs
- Stratosphere - protective layer
- Mesosphere
- Thermosphere
- Exosphere
What is the difference between weather and climate
- Weather describes the atmosphere conditions at a specific place and time
- Climate describes the average conditions expected at a specific place and time
What is global atmospheric circulation?
- Defined as a wind system with annual and seasonal variations
What is solar radiation?
- Provides the energy to drive the global atmospheric circulation
- Not evenly distributed over earths surface
- The same amount of incoming solar radiation is spread out over a larger area near the poles due to the earths tilt
Why does the wind blow at the surface and in the atmosphere
2 reasons
- Solar radiation
- Earths rotation
How does the earths rotation control why the wind blows on the surface and in the atmosphere?
- The Coriolis effect - a force that makes wind swirl clockwise in Southern Hemisphere and anticlockwise in Northern Hemisphere
- This determines the shape of global atmospheric circulation
What is the 3 cell circulation model of the atmosphere
1) Hadely cell - tropical
2) Ferrel cell - mid latitude
3) Polar cell
- Involves the convection of hot and cold air
- Surface winds not directly north or south du to earths rotation
- This forces air to move is easterly and westerly direction
What is the intertropical convergence zone?
A narrow zone near the equator where northern and southern air masses converge, typically producing low atmospheric pressure - lots of rain
Outline global cloud cover
- Rising warm air carries water vapour
- As air cools the water vapour condenses forming clouds
What is heat?
- Heat is the amount of energy of all molecular movement inside a body
- It is transferred from high temp to low temp bodies by a variety of different processes
What is temperature?
- Temperature of the air is a measure of the internal energy of the air (speed of air)
- This internal energy is associated with random motion of molecules
What is absolute zero?
- The temp below which the temp of any substance cannot fall
- Molecules have zero energy
How is heat transferred?
It is transferred from high temp to low temp bodies by a variety of different processes
What is conduction?
- The transfer of heat by molecular impact without the transfer of matter itself
- How heat travels between objects in direct contact
- Due to temp difference, occurs in solids at low speeds
What is convection?
- The transfer of heat by real movement of matter that occurs only in molecules that are free to move from one place to another
- Occurs in gases and liquids
- Due to density difference, it uses intermediate substance at low speed
What is radiation?
- The transfer of heat from a body with a temp higher than absolute zero
- Uses electromagnetic waves at fast speed at high temp with shorter wavelengths
What is long wave radiation?
- The ground heats up and re-emits energy as long wave radiation in the form of infrared rays
- Apart of terrestrial regime
- Wave length of 4 -100
What is short wave radiation?
- The sun emits shortwave radiation as it is very hot and has a lot of energy to give off
- Wavelength less than 4 due to high temp of suns surface
- Apart of solar regime
What is global radiation?
- The sum of all short wave radiation received from direct solar radiation and indirect diffuse radiation
- Result of scattering and absorption of radiation in clouds
- Reflects astronomical factors and distribution of clouds
- Shows strong diurnal variation in intensitiy
How is radiation distributed?
- Highest radiation is on side of the equator
- Due to solar angle and global cloud cover
What is the albedo effect?
Light surface reflects more heat than dark surfaces
What is surface albedo?
The fraction of shortwave radiation received that is reflected by a surface
What is planetary albedo?
The reflection of shortwave radiation by the whole planet with 3 elements:
1) radiation reflected by land or sea surface
2) radiation reflected by clouds
3) radiation back scattered by the atmosphere
What is net radiation?
- The difference between the total incoming and total ongoing radiation
- Averaged over the year, there is a net energy surplus at the equator and deficit at the poles
- This equator vs pole imbalance is a fundamental driver of atmospheric and oceanic circulation
