Weight of air at sea level
- 14.7 lbs. per square inch
- 1 kilogram per square centimeter
Barometer
- instrument used to measure pressure
-1st was made of mercury (hazardous), we now use aneroid barometer (without liquid)
factors affecting wind
- Horizontal movement of air (from high pressure to low)
- controls of wind
- upper air winds
isobars
lines of equal air pressure
pressure gradient
pressure change over distance
geostrophic winds
blow parallel to isobars
(weather in US moves west to east)
cyclone
a center of low pressure
high pressure
high and dry weather
- anti-cyclones
low pressure
stormy and wet weather
anti cyclones
- northern hemisphere clockwise winds
- southern hemisphere clockwise winds
- fair weather
(low pressure)
trade winds
- wind blowing steadily toward the equator from the northeast in N Hemisphere and southeast in S Hemisphere
westerly winds
- winds from west to east
- originate from high pressure areas
- AFFECT U.S.
3 types of local breeze
land and water, mountain and valley, dry desiccating
land and water breeze
blows from water to land during the day, opposite at night
mountain and valley breeze
- warm air rises from the valley
- mountain breeze moves to valley at night
chinook
snow year round
santa anta winds
- dry desiccating winds out of mountains
- bad news for fires
anemometer
measures wind speed
speed and direction
used to measure wind
weather vanes or compass points
measures wind direction
gulf coast/southeast
San Antonio winds predominately from _____________.