Wind & Weather Basics March 2014
Weather is always changing ! Constant movement of air Changes in moisture
Air Mass Large body of air that has the same properties as the surface over which it develops. – Cold, Hot- Wet, Dry These air masses move across the U.S. & collide with each other creating fronts ….….
Types of Air Masses
Weather Maps
Tuesday & Wednesday
Isotherms
Isobars
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Cloud Formation
Condensation level = bottom of the clouds
Clouds may form by Forceful Lifting May occur when air goes up the side of a mountain Also occurs when air is lifted during storms
Advective Cooling Occurs when wind blows warm, moist air over a cold area such as a lake or ocean.
Types of Clouds
Fog = low stratus cloud
How does weather affect you? Directly – Rain – floods/drought – Snow – closes school – Ice – no power – Tornado – destructive Indirectly – Drought – food prices go up – Freeze in South – fruit is destroyed – Cold Weather – oil & gas prices go up
What determines what the weather will be today? Air pressure Wind Temperature Humidity
Wave Cyclones Low pressure areas Start to rotate counterclockwise Bad weather Thunderstorms & rain
Air Pressure Low Pressure Few molecules in the air “sucks in” bad weather
Hurricanes = Tropical cyclones Also known as typhoons Speeds in excess of 120 km/hr
Thunderstorms
Tornadoes
Anticyclones High pressure areas Dry/clear weather Droughts "High pressure is good; sunny weather occurs when the pressure is high. Skies are blue, winds are light and it never rains when the barometer soars."
Air Pressure High Pressure Lots of molecules in the air “pushes away” the bad weather
Complete Venn Diagram for High & Low Pressure Systems
03/22/ Updated 02:02 PM ET Source: USA TODAY research by Chad Palmer, Graphic by John He
03/22/ Updated 02:36 PM ET Source: USA TODAY research by Chad Palmer, Graphic by John Herne
Occluded Fronts 2 cold air mass meet Pushing up the warm air that is blocked in-between. 03/22/ Updated 02:29 PM ET 03/22/ Updated 02:29 PM ET
Stationary Front
Each Front causes precipitation Along each front warm air is pushed upward, cooled in the atmosphere, and becomes saturated
Types of Fronts
Start here on Wednesday
Weather Instruments & forecasts
Anemometer Measures wind speed
Wind Comes from North => Cold Comes from South => Warm Fast or Slow ???
Weather Radar = Doppler Radar
Measuring air pressure with a barometer
Humidity Hot air can hold more water vapor Cold air is drier & causes static electricityin winter Measured with a psychrometer, hygrometer, or a
Relative Humidity The amount of water vapor in the air compared to how much it could hold. ex.) 50%, 20% Saturated means 100% Measured with a psychrometer.
Radiosonde = package of weather instruments
Climate: predictable weather patterns