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Geos 114

Geos 114. Introduction to Meteorology. Definitions. Meteorology Study of the atmosphere & the processes that causes weather Weather State of the atmosphere at a particular place & time. Described by T, Humidity, Ppt., Wind speed Climate

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Geos 114

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  1. Geos 114 Introduction to Meteorology

  2. Definitions • Meteorology • Study of the atmosphere & the processes that causes weather • Weather • State of the atmosphere at a particular place & time. Described by T, Humidity, Ppt., Wind speed • Climate • Average values of weather conditions at some place for at least 30 years beginning with the first year of a decade (i.e. 1971-2000; average annual and monthly temp, ppt). Tabulation of extreme events during time of record i.e. high/low T, greatests snowfall, most intense rainfall) • Climatology • Study of climate, control, spatial and temporal variability

  3. Climatic Zones • Tropic Humid (A) • Dry Climates (B) • Steppe (BS) and desert (BW) • Subtropical Climates (C)- Mediterranean • Snow Forest Climates (D)- temperate continental (i.e. northeast US) • Polar Climates (E)- poleward of arctic & antarctic circles • Highland Climates (H)- mountanous terrain every 300 meters of altitude is equivalent to 500km of latitude.

  4. Climatic Zones

  5. Sources of Weather Info • Weather Radio • Low Power VHF High Band FM • Constant weather information • Repeat messages every 4-6 minutes • Transmits all other sorts of emergencies • Cable & Broadcast TV • The Weather Channel • WWW

  6. NOAA Weather Radio

  7. The Weather Channel

  8. Intro to Weather Systems & Maps • ASOS: Automated Surface Observing System (installed at airports) records 24hrs/day • Temp., humidity, dew point, wind speed & direction, Pressure

  9. ASOS

  10. Pressure Systems • Pressure: weight per unit area of a column of air stretching from the earth’s surface up to through the atmosphere • Highs (anticyclones) • ‘H’ on a map • Fair weather systems • Cold or cool, dry air (NW Canada) • Hot, mild, dry air (from land further south) • Clockwise, outward spiral • Lows (cyclones) • ‘L’ on a map • Stormy weather systems • Counterclockwise, inward spiral • Highs and lows move with prevailing winds (eastward in North America)

  11. Pressure Systems L H

  12. Air Masses • Large uniform air mass (temperature and humidity) associated with high pressure system • Cold air masses form at high latitudes • Humid air masses over maritime surfaces • Dry air masses over arid/semi arid regions • Cold & Dry • Cold & Humid • Warm & Dry • Warm & Humid

  13. Fronts • Narrow band between 2 air masses that differ in T, humidity, or both • Fronts form where air masses collide • Ppt & cloudiness • Fronts: • Stationary • Cold • Warm

  14. Fronts

  15. Fronts

  16. Vocabulary • Max. T (oF; oC) • Min. T • Dew Point • Relative Humidity (%) • Ppt. amount • Air pressure (29.92 inches, 760 millimeters Hg; millibars (mb) 1013.25mb at sea level) • Wind direction; speed • Sky cover (no clouds; few (1/8-2/8 cloud cover); scattered (3/8-4/8); broken clouds (5/8-7/8); overcast (completely cloud covered)) • Weather watch- NWS possibility of hazard • Weather warning- NWS imminent hazard

  17. Weather Satellites • GOES (geostationary operational environmental satellite) • 36,000km (22,300mi); equatorial, eastward motion, same view 75oW, 135oW • POES (polar-orbiting operational environmental satellite) • N-S orbit 800-1000km above surface • Measure visible radiation that is scattered or reflected and infrared

  18. GOES

  19. Weather Radar & Doppler • Complements satellite data • Microwave radiation • Emits pulses that are reflected by rain, snow, hail which appear as blotches known as echoes • Doppler determines velocity of targets moving towards or away from unit depending on frequency bet. Outgoing & returning signal • Monitor circulation of air within a storm system and provide advance warning of severe weather

  20. Doppler Radar

  21. Sky Watching • Clouds- aggregates of water droplets or ice crystals or both • Fog- ground contact cloud reduces visibility to less than 1000m • Stratiform- horizontal layers, gentle rising of air over broad region ahead of a warm front • Cumuliform- puffy, vigorous ascent of warm air ahead of a cold front

  22. Clouds • Fair weather cumulus clouds • Storm cumulonimbus clouds produce lightning & thunder • Clouds at different altitudes may move horizontally in different directions and speeds

  23. Cloud Types

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