Earth and Environmental Systems
Why does the wind blow?
Air moves from high pressure to low pressure
Differential pressures caused by differential heating
1) small scale = lake effect
2) larger scale = sea breeze
3) global scale = wind belts
What kind of air is the least dense (most likely to rise)?
Hot and Humid air
What happens to a rising parcel of air that could cause it to become saturated with water, and what would happen to that same parcel of air if it began to sink, and what type of surface pressure would you expect for each?
Rising-Low pressure
1) expands
2) cools
3) be able to hold less water- relative humidity rises
4) if RH reaches 100% water condenses
5) continued condensation leads to precipitation
Sinking-High Pressure
1) contracts
2) heats
3) holds more water-relative humidity sinks
4) if RH reaches 100%, water evaporates
What are the definitions and values for dry adiabetic lapse rate (DALR) and saturated adiabetic lapse rate (SALR)?
DALR: dry humidity decrease in temp with increase in elevation- about 1 degree C /100m. Dry
SALR: once the water in the air begins to condense, it releases its latent heat- about .5 degree C/100m. Higher temp=lower SALR

Lifting Condensation Level (LCL): the temp at which water begins to condense

Besides DALR and SALR, what else do you need to know about the atmosphere to determine if the air is stable or unstable?
Environmental Lapse Rate (ELR): temp of the surrounding air as a function of altitude
What are the five ways to lift air so that clouds and precipitation can form?
1) Global convection cells
2) local convective heating
3) orographic lifting
4) weather fronts
5) surface convergence and upper level divergence
Know the name of the apparent force that causes moving objects to change direction on the surface of the Earth, its relationship to the object’s velocity, and which way does it cause objects to deflect in the Northern and Southern hemispheres?
Coriolis Force: C = 2V-12Sinx
an apparent force proportional to velocity
deflects objects to the right in the Northern Hemisphere and to the left in the Southern Hemisphere
Strongest at the poles, weakest at the equator
If you are in the Northern Hemisphere, what would you do to determine the position of low surface pressure relative to your position?
Back to the wind, point left (Towards low pressure)
30 degrees to the right
Know the basic pattern of the three cell model of global circulation and know which direction winds blow at the surface in each, and the name of the climatic zones they create.
0 to 30: Tropics, NE to SW winds
30 to 60: Temperate, SW to NW winds
60 to 90: Polar, NE to SW Winds
What two latitudes do you expect to find significant precipitation, and what two do you expect to find little precipitation?
Significant: 0 and 60
Little: 30 and 90
Know the difference between a sea breeze and a land breeze in terms of time of day, wind direction at the surface, pressure at the surface, and where precipitation is most likely to occure
Sea Breeze: sea to land, during the day, high pressure over sea, low pressure over land, precipitation over land
Land Breeze: exact opposite
What is a rain shadow, and how does it form?
Rain Shadow: The area downwind from a mountain that receives little or no rain
Know which kind of front tends to bring the most severe storms.
Cold. Move slowly at about 5-10mph
What type of upper air flow leads to low surface pressure?
Upper level divergence
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