The exam will be 80 questions, multiple choice. You may use a calculator, however, CELL PHONE USE IS PROHIBITED. Please bring a #2 pencil. Study aids: This sheet, lecture notes, textbook. Learn and be able to apply concepts; do NOT simply memorize facts. Questions? Come to office hours, ask your TA, post to the discussion board on Compass. FROM BEFORE:
_What is the difference between satellites and radar?
1. Satellites: View clouds from space
a. Radar: View precipitation from ground
_How is wind direction defined?
1. Wind Direction: Direction FROM which the wind is blowing a. i.e. A north wind blows from the north (toward the south) b. Stick on weather map identifies wind direction
_How do winds blow about high and low pressure systems in the Northern Hemisphere? 1. Low pressure: counter-clockwise and inward (air converges and rises leading to clouds, rain) a. High pressure: Clockwise and outward (sinking air leads to clear skies) _What is pressure and how does in change with height?
1. Pressure: Force/Area; molecules in given area
a. it always DECREASES with height
_What is an inversion?
1. Inversion: Layer in which the temperature increases with height _What is latent heat?
1. Latent heat: The energy absorbed or released during a phase change a. “Hidden” energy
· _What is advection?
a. Advection: Transfer of heat (or moisture) through horizontal movements of air _What is saturation? What mathematical relationships are true at saturation? 1. Saturation: an atmospheric condition where level of water vapor is the maximum possible at the existing temp and pressure; equal rates of evaporation and condensation a. Air is not a “sponge”- air is NOT so “full of water” that there is no room for anything else; molecules very far apart b. Most of an air molecule is empty space
_What is relative humidity? How can it be changed?
1. Relative Humidity: ratio of water vapor in air that is required for saturation a. Does NOT indicate actual amount of water vapor in air i. Higher RH does NOT necessarily mean there is more moisture in air ii. ******Higher RH MEANS air is closer to saturation****** b. At saturation, RH = 100% (VP=SVP)
c. RH=(VP/SVP) x 100%
d. Increase RH: 1) Add moisture to air (increase VP) or cool air (decrease SVP)
_What is dewpoint? Why is it useful?
1. Dewpoint: as we cool air, temp at which saturation occurs; when surface cools below that temp dew (condensation) is created; frost forms if surface cools below freezing a. Can saturate air in two ways
i. Add water to air (keep temp constant)
ii. Cool air (keep moisture content constant)
b. ********Higher dewpoint temp ALWAYS means more moisture in the air******** iii. Warmer air ALWAYS contains more moisture at saturation than does cold air c. Dewpoint is ALWAYS less than or equal to the temp
iv. Takes units of temp (oF, oC)
d. As dewpoint increases, vapor pressure increases
e. On most days, can get a first-guess forecast of overnight temp by looking at afternoon dewpoint 2. Best way to compare atmospheric moisture concentrations between two locations??????? Whichever location has higher dewpoint _How do clouds form?
1. As air rises, it expands and cools
a. Amount of water vapor in air does not change as air rises b. Relative humidity increases
c. Air eventually rises high enough (cools enough) to become saturated (RH=100%) 2. Clouds are made of billions of microscopic water droplets or ice crystals d. Water droplets attach onto condensation nuclei and condense 3. Condensation nuclei: dust, ash, smoke, pollution, salt, plankton, etc. HYDROPHILICattract water e. Important because water droplets REQUIRE surfaces on which to condense _How do you...