General Circulation ATPL Flashcards
State the dominant factors that control the transfer of heat around the globe. (8)
Short wave solar radiation and long wave terrestrial radiation
•Conduction from Earths surface to 10cm up
•Convection for vertical transfer of heat thereafter
•Advection through wind/systems
Release of latent heat during cloud development
•General circulation which is constantly trying to correct the temperature imbalance between equator and poles
•The seasons
•Sea currents
Explain zonal index
Strength of the pressure gradient (westerly wind) between 35ºS and 55ºS and mirrored in Northern Hemisphere
Explain zonal winds
Refers to if the wind is positive (westerly)
Or negative (easterly)
Describe high zonal index
Suggests a strong pressure gradient from north to south.
Anti-cyclone will be to the north and depression to south in southern hemisphere. Reverse in northern
Creates strong westerlies
Describe low zonal index
Depression will be to the north and anticyclone to the south. Reverse in northern hemisphere
Creates easterlies if very weak but normally westerlies
Pressure gradient is now negative from 35ºS to 55ºS
State how high zonal index and low zonal index relate to the speed and direction of low tropospheric systems
•All systems move west to east due to the rotation of the Earth
•High zonal index cause systems to move rapidly from west to east as the westerly increases their horizontal speed
•Low zonal index cause systems to move slowly from west to east or stop completely creating blocking highs
State how high zonal index and low zonal index relate to the strength and uniformity of upper-level westerlies and jet-streams
Stronger and more uniform with high zonal index
Weaker and less uniform with low zonal index
Define long atmospheric waves
Know as planetary or Rossby waves
Naturally occurring waves which form in rotating fluid that migrate west to east like a river that jet streams flow down.
Long waves have 1-3 wavelengths and transport warm air from the tropics to the poles and cold air to the tropics.
Define medium atmosphere waves
4-7 wavelengths around the planets in size.
responsible for highs, lows, fronts, tropical cyclones and warm/cold pools
Define short atmospheric waves
8 wavelengths or greater and are short lived which cause gusts, thermals, local winds and rotor zones.
Where the waves are out of phase to each other they’ll cancel each other out
Define cold pool
Occurs when long waves make large north south meanderings in a low zonal index situation
•Bubble of cold air in mid to upper troposphere
moves from high latitudes to warmer lower latitudes
•The cold pool is cut off and surrounded by warmer air
•Steepens ELR intensifying low pressure systems
Where do cold pools originate and what do they associate with
Originated from latitudes with permanent lows therefore carries those characteristics into the lower latitudes all the way to the surface
•Are associated with instability
Define what is meant by warm pool
Opposite of cold pool
•Bubble of warm air in mid to upper troposphere moves from low latitudes to colder higher latitudes
•The warm pool is cut off and surrounded by colder air
•Shallows ELR intensifying high pressure systems stability
Where do warm pools originate forms and what are they associated with
Originated from latitudes with permanent highs therefore carries those characteristics into the higher latitudes all the way to the surface.
Associated with stability.
What’s an air mass
Air mass is the meteorological term for a volume of air with a constant temperature and humidity covering an area. It varies in size from hundreds to thousands of miles. It remains positioned over a region for extended periods and, as a result, takes on the characteristics of the surface it covers.
