Atmospheric Processes Flashcards
What are the 5 components of the climate system?
Atmosphere Hydrosphere Cryosphere Land surface Biosphere
What is the main energy input into the climate system?
Solar energy
What are the annual and seasonal variations in wind systems caused by?
Coriolis effect
Inequalities in the distribution of solar radiation leading to atmospheric circulation.
What are the 3 cells in the cell circulation model?
Hadley
Ferrel
Polar
What is the Polar Front?
The boundary between the Ferrel and Polar cells
What is the pressure like at the Polar Front?
A low pressure zone where warm, moist air from the Ferrel cell runs into relatively cold, dry air from the Polar cell
Why is the positioning of the Polar Front important?
Weather is variable here
What does ITCZ stand for?
Inter-Tropical Convergence Zone
Where is the ITCZ located?
Near to the equator, where the trade winds of the Northern and Southern Hemispheres come together
What happens at the ITCZ?
Intense sun and warm water warm the air and make it humid. This leads to thunderstorms as the air rises causing it to expand and cool.
How does the ITCZ affect the climate around the equatorial regions?
The equatorial regions experience wet and dry seasons rather than hot and cold.
What are the two reasons for seasonal differences in climate across the globe?
Spherical shape of the Earth which also leads to large N-S temperature differences.
Tilt of the Earth’s axis of rotation
What degree is the tilt of the Earth’s axis?
23.5
What are Trade Winds?
Equator-ward flowing easterly winds
What is the Jet Stream?
Relatively narrow bands of strong wind in the upper atmosphere. Embedded in Rossby waves.
In which direction does the Jet Stream flow?
From west to east
When is the Jet Stream strongest?
In Northern and Southern Hemisphere winters
What does the first law of thermodynamics state?
Energy can be converted but not created or destroyed.
What is responsible for the formation of weather systems?
The transformation of heat into mechanical energy.
What is entropy?
The measure of unavailability of heat energy for conversion.
What is the second law of thermodynamics?
Entropy increases with time, so overtime the system becomes more disordered
According to the second law of thermodynamics, what will happen to organised atmospheric motion overtime?
It will break down
What does medium and large atmospheric motion show?
A high degree of stability, suggesting that entropy does not increase with time and that there is a source of low input entropy.
What objects emit radiation?
Anything above absolute zero
What determines the intensity of insolation on the ground?
The angle of the Sun’s energy
What is temperature?
The mean kinetic energy per molecule of an object
What is heat?
Measure of total kinetic energy
What happens to molecules at absolute zero?
They are at rest
What is latent heat?
Heat that is stored and used when a substance changes state.
What is latent heat transfer?
Transfer of heat from an evaporating surface to the atmosphere.
What do heat transfer processes include? (2)
Conduction and convection
What is insolation?
Incoming solar radiation
What are the units of insolation?
Wm-2
What does insolation vary by? (2)
Latitude and season
Which objects emit more energy at shorter wavelengths?
Hotter objects
What is the change in state for sublimation?
Solid to gas
What happens to the latent heat in sublimation?
Latent heat is absorbed
What is the change in state for deposition?
Gas to solid
What happens to the latent heat in deposition?
Latent heat is released
What happens to the latent heat if a substance becomes less disordered?
Latent heat is released.
What is albedo?
How reflective the Earth’s surface is
What will happen to albedo as a result of sea ice decline?
Less solar energy will be reflected leading to more absorption by the sea.
What are the two types of radiation?
Direct solar radiation or indirect diffuse radiation
What do clouds trap?
Radiation
What is net radiation?
The difference between incoming and outgoing radiation
Where is there an energy deficit?
At high latitudes
Where does heat transfer move surplus energy?
From low to high latitudes
What does radiation not require to travel?
Radiation
What structures does radiation have?
Both a wave and photon structure
What wavelength is solar radiation?
Shortwave
What wavelength is terrestrial radiation?
Long wave
How does temperature control the amount of radiation emitted?
The higher the temperature, the more radiation emitted
What does the global water balance constantly cycle between?
Stores
What part of the hydrological cycle contains little water?
The atmopshere
What part of the hydrological cycle is responsible for the largest flow of water?
The atmosphere
What is humidity?
The amount of water vapour in the atmosphere
What type of air can hold more water vapour?
Warm air can hold more water vapour than cold air
What is relative humidity?
Saturated air
What happens to air as it rises?
It cools and becomes saturated
What is the dew point?
The temperature of saturation
What happens after the dew point is reached?
Condensation occurs, dew forms and it may rain
What decreases as temperature increases?
Relative humidity
What happens as a gas expands?
Its volume increases and its pressure and temperature decrease
What does the adiabatic lapse rate do?
Quantify how the temperature of air decreases as it rises
What can cause the adiabatic lapse rate to differ?
Wet and dry masses have different rates
What happens to the dew point as air rises?
The dew point decreases
What is the dominant process for transferring heat?
Convection
What do temperature variations occur with?
Vertical motions
What is meant by the term adiabatic process?
Energy is transferred in the form of work to or from the system
What does mass balance dictate?
Some air masses must rise and some must fall
Where does overturning occur?
In the troposphere
What is overturning?
The constant turning of the atmosphere
What is the dry adiabatic lapse rate?
Rate of temperature fall with height
What is dry adiabatic lapse rate measured in?
C/Km
What is the saturated adiabatic lapse rate?
Rate in the presence of condensation
When is the complete earth- atmosphere system in thermal equilibrium?
Over long time scales
Where is heat energy transferred to?
From the tropics to the poles
What transfers heat energy from the tropics to the poles?
The north-south circulations in the atmosphere and oceans
What is airflow almost parallel to?
Isobars
Where is airflow not almost parallel to isobars?
Near the surface and the equator
At what angle should air move to the isobars?
90 degrees
Why doesn’t air move at 90 degrees to the isobars?
Due to the Earth’s rotation
What are geostrophic winds?
Deflected winds that are more than 1km above the surface
What is speed proportional to in geostrophic winds?
Speed is proportional to pressure gradient and strength of Coriolis effect
In which direction is air flow for geostrophic winds?
Anti-clockwise around low pressure in the Northern Hemisphere and clock wise in the Southern Hemisphere
What are Rossby waves the result of?
Smooth westward flow of upper air westerlies
Where do Rossby waves develop?
At the Polar Front- they form convoluted waves that eventually pinch off
What mechanism are Rossby waves for?
They are the primary mechanism for poleward heat transfer
What creates low pressure?
Pools of cool air
What is the Jet Stream caused by?
Sharp temperature differences
Where is the subtropical westerly jet stream?
Poleward boundary of the tropical Hadley cell, just below the tropopause
What does the subtropical westerly jet stream divide around in winter?
It divides around the Tibetan Plateau
When does the equatorial easterly jet stream develop?
It develops in summer when the northern subtropical westerly jet stream is less developed and moves poleward.
What is the equatorial easterly jet stream connected with?
The formation of a high pressure, upper level system over Tibet
What is the Polar front jet stream associated with?
Warm and cold fronts of temperate latitude depressions.
Which jet stream has considerable day to day variations?
The Polar front jet stream
What is the climate system based on?
Ocean-atmosphere interactions
What are 3 ocean- atmosphere interactions?
Albedo, moisture circulation and energy transfer
What allows ice to form on the surface of oceans when warmer air resides below?
Density profiles of water
What does ice influence?
Albedo and surface winds
What does the North Atlantic circulation bring?
A continuous supply of heat and moisture to Western Europe
Why is the North Atlantic circulation more noticeable in winter?
The area is milder than other areas in the same latitude
What is El Nino Southern Oscillation?
An air exchange between South Pacific high and Indonesian equatorial low
How long is the ENSO cycle?
2-8 years
What happens to the trade winds during La Nina?
They are intense
What happens to the western tropical Pacific during La Nina?
The warm tropical waters converge
What happens to the eastern tropical Pacific during La Nina?
It is cold and dry
What happens to the trade winds during El Nino?
They relax
Where do warm waters move in El Nino?
Eastwards
What happens in the Western Tropical Pacific in El Nino?
Drought
What does the Eastern Tropical Pacific receive during El Nino?
Heavy rainfall and floods
