Chapter 6 a Atmospheric pressure i The mass of air above a given level ii Winds always move form high pressure to low pressure for the most part iii The force exerted by the air molecules over a given area b Millobar c i A unit of atmospheric pressure Isobars i Solid black lines drawn on a surface map to depict the differences in pressure ii Used to determine where highs and lows are d Forces that influence the wind i Pressure gradient force 1 Air moving from high pressure to low pressure ii Coriolis force 1 The apparent force that is due to the rotation of the earth 2 Makes wind deflect to the right in the Northern Hemisphere 1 Inward directed force that acts around highs and lows 1 Frictional drag of the ground that slows down wind vectors which weakens iii Centripetal Force iv Friction force Coriolis force v Vertical motion 1 Near surface LOW air rises a Convergence at the surface divergence aloft 2 Near surface HIGH air sinks a Divergence at the surface convergence aloft vi Wind Direction and Speed 1 Hydrostatic Equilibrium pushes up a When gravity and pressure gradient are of equal force pressure gradient b Only is it not equal during thunderstorms because of the updraft Chapter 7 Atmospheric Motion Eddies Rotors o A whirl of air downwind from a solid object o Eddies that form under each wave crest in the air flow Have violent vertical motion that produces extreme turbulence and hazardous flying conditions Wind shears o Wind change in speed and direction that is abrupt Cause turbulence aloft o Clear air turbulence Created by wind shear aloft Thermal Circulation Movement of air by heating and cooling o Hot air rises creating lows at the surface and highs aloft Cold air sinks creating high at the surface and low aloft o These effects create a circulation that creates land breezes and sea breezes Valley Breeeze Warming of air at bases of the mountain making it rise and converge at the peak o Forms clouds and upslope wind Mountain Breeze Cooling of mountain air on its slopes causes the air to sink o Reverse at Valley Breeze o Causes downslope wind at night Katabonic wind Any downslope wind that goes from high pressure to low pressure over a high plateau o Born in Yugoslavia o Mistral in France o Coho in Seattle U S Chinook wind Katabonic wind that warms extremely fast when coming downslope compressional heating o Produces hot dry air o Produces wall of clouds at the mountain peaks o Occurs mostly eastward over the Rocky mountains Santa Anna Wind Katabonic wind that descends down the mountains toward Los Angeles Southern Cali Fuels wildfires when they occur in the summer Haboob Dust Devils Dust clouds that form over deserts and move to the cities Form when cold downdrafts along the leading edge of a thunderstorm lift dust into a huge dark cloud Small circulation vortexes of sand that can occur in clear skies Form when wind bends around trees and other solid objects Global Winds and Cells o General Circulation of the Atmosphere Single cell model Hadley Assumes that The alternating heating between land and sea does not come into play The winds don t shift seasonally There is no Coriolis effect Says that heating by the sun at the equator makes the air rise which flows to the lower pressure cool poles This creates different climate regions of world THIS IS WRONG Three Cell model Hadley cell between the doldrums and subtropical high o 1 Doldrums where trade wind converge at the quator making winds light and pressure gradient weak Ferrel Cell between the subtropical high and subpolar low o Subtropical high divergence of air due to the convergence aloft by the Ferrel and Hadley cells This is because of heating lows at the equator and 60 degree parallel horse latitudes Polar cell between subpolar low and polar high o Winds within these cells Trade winds surface winds that move at an angle from the subtropical high to the doldrums Westerlies surface winds that move at an angle from the subtropical high to the subpolar low Intertropical convergence zone o At the equator where the NE and SE trade winds converge creating thunderstorms all along the area o Usually where hurricanes are formed Jet Stream place o Occur between ciruculation cells where advection takes o Encircle the Earth o Occur in the tropopause at the subtropical high the subpolar low o Flow in wavy patterns from east to west La Nina High pressure over south Americas pacific coast Low pressure over Indonesia produces easterly trade winds These winds produce upwellings along the South American coast of deep cold water that is nutrient rich o Makes for amazing fish industry The winds also push arm water toward Indonesia and lows that produce heavy rainfall El Nino The roles are reversed High pressure over south Americas Pacific coast decrease and high pressure rises over Indonesia this change cause trade winds to weaken or reverse entirely A counter current occurs that brings warm water to the south American coast that is very low in nutrients The seesaw pattern changing atmospheric pressures on opposite Southern Oscillation ends of the pacific Global Effects During el Ni o years subtropical jet stream brings storms toward Cali and heavy rain not severe storms to the gulf coast of Florida Chapter 8 1 Air masses constant through 2 Source region a An extremely large body of air whose properties of temperature and humidity are fairly a Where the air mass originates area should be generally flat and of uniform composition b with light surface winds Ideal regions are those dominated by high pressure i Middle latitudes are not good source regions this is where a wide range of weather activity occurs c It is usually altered after leaving the region 3 Types of Air masses a Continental Arctic cA i Shallow small vertical development ii Extremely cold iii Dry and stable iv Usually ice and snow covered surface b Continental Polar Air i Cold dry and stable ii Can be modified by warm water to be warm and moist c Maritime Polar i Cool moist and unstable ii Picks up moisture and dumps it on land rotates counterclockwise iii Mostly occurs along cost of California iv Air dries as it passes over mountains heading inland v Also occur in EASt coast Canada and Northest U S as back door fronts rotates clockwise and moves from east to west instead of west to east 1 Lost of clouds flow northeast from Hawaii and produce heavy rain and flooding d Maritime Tropical i Mostly occurs in Florida and East coast ii Warm moist and unstable iii Pacific Pineapple
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