Weather and Climate Terms: Atmospheric Conditions, Air Masses, and Tropical Cyclones, Quizzes of Geography

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TERM 1 Weather DEFINITION 1 the short term, day-to-day condition of the atmosphere TERM 2 Climate DEFINITION 2 Long term average TERM 3 Meteorology DEFINITION 3 Scientific study of the atmosphere TERM 4 Air Mass DEFINITION 4 Earth's surface shares its temperature and moisture conditions with overlying air Creates regional air masses with similar temperature, humidity, and stability throughout distinctive body of air Initially reflects characteristics of source region --> where the mass starts from TERM 5 Classification based on two variable DEFINITION 5 Temperature P = Polar T = tropical A = Arctic E = equatorial AA = antarctic Humidity M = maritime C = continental Air masses effecting North America TERM 6 Continental Polar DEFINITION 6 cP form only in northern hemisphere and are most developed in winter (and cold-weather months) Major player in middle and high latitude weather Cold, dense cP air displaces warm, moist air Produces lifting, cooling, and condensation Area covered by cP air in winter = cold, stable air, clear skies, high pressure, and anticyclone wind flow TERM 7 Maritime Polar DEFINITION 7 mP in the NH these exist over the northern oceans Cool, moist, unstable conditions Aleutian and Iceland subpolar low pressure cells exist within these mP air masses (especially in winter) TERM 8 Two exist that influence North America DEFINITION 8 Over the Gulf/ Atlantic Influences East and Midwest - unstable and active from late spring to early fall Over the Pacific Stable to conditionally unstable, generally lower in moisture and energy than Gulf/ Atlantic mT. Influence Western U.S. with lower average precipitation than rest of U.S. TERM 9 Air Mass Modification DEFINITION 9 As air masses migrate, their characteristics will slowly change based on surface characteristics For example, the mT Gulf/ Atlantic may carry humidity to Chicago and on to Winnipeg, but it will gradually lose its warmth and humidity with its movement northward Another example, cP changes as it moves south and east to produce snowbelts that lie to the east of each of the Great Lakes (Ex: lake-effect snow) As cP passes over the warmer Great Lakes, it absorbs heat energy and moisture TERM 10 Convergent Lifting DEFINITION 10 air flowing into same low pressure area converges and displaces air upward occurs along the equator, forms ITCZ TERM 21 Storm Tracks DEFINITION 21 path across continent MLCs can be 1,600 km wide Further north in summer, south in winter Regional names Where cP and mT meet in spring we have potential for many tornadoes TERM 22 Bomb DEFINITION 22 Explosive cyclogenesis is called a bomb When extratropical cyclone deepens rapidly Barometric drop at least 24 mb in 24 hours For example: One case of 60 mb because in central pressure in 24 hours --> 2.5 mb/ hour TERM 23 Analysis of daily weather maps DEFINITION 23 Forecasting TERM 24 Synoptic analysis DEFINITION 24 evaluation of weather data at specific time TERM 25 Numerical weather prediction DEFINITION 25 using database of wind, pressure, temperature, and moisture conditions to forecast TERM 26 Weather related issues DEFINITION 26 More than 10 billion per year through the 1990s Katrina and remaining hurricane season (2005) > $130 billion Gustav and Ike (2008) > $100 billion TERM 27 Thunderstorms DEFINITION 27 When water vapor condenses, large amounts of energy are released Locally heats air violent updrafts and downdrafts as rising air pulls in surrounding air Can develop within air masses, along fronts, or where mountains cause lifting Severe thunderstorms: require one additional ingredient -- > Shear TERM 28 Three ingredients to form thunderstorm DEFINITION 28 Moisture Instability A lifting mechanism TERM 29 Developing or Cumulus Stage DEFINITION 29 Dominated by updrafts caused by surface convergence Bergeron process builds precipitation which is supported by the updrafts TERM 30 Mature Stage DEFINITION 30 Updrafts and downdrafts side-by-side and precipitation begins to fall Downdrafts caused by falling precipitation causing drag on the air and also by the influx of cool, dry air that tends to sink Entertainment is the process of the influx of cool, dry air TERM 31 Dissipating Stage DEFINITION 31 Downdrafts and entertainment dominate and thus the storm loses its supply of energy i.e. warm moist rising air, and it begins to dissipate Light precipitation until the storm dissipates TERM 32 Atmospheric turbulence DEFINITION 32 Downbursts: exceptionally strong downdrafts Macrobursts - 4 km wide and > 210 kmph Microbursts - smaller in size and speed Rapid changes in wind speed and direction = wind shear can bring down airplanes TERM 33 Lightning DEFINITION 33 Flashes of light caused by electrical discharges (over 100 million volts) Caused by polarity of cloud base and the ground Superheats air over 30,000 degrees C Cloud to cloud lightning Cloud to ground lightning TERM 34 Thunder DEFINITION 34 When lightning strikes the violent expansion of heated air sends shock waves through the atmosphere as sonic booms TERM 35 Derechos DEFINITION 35 straight line wind storms Winds in excess of 58 mph Significant damage and crop loss HIghest frequency from May thru August Iowa across Illinois, into the Ohio River Valley From September through April - move south (eastern TX and AL) 1998 eastern Wisconsin = exceeded 128 mph TERM 46 Tropical cyclones DEFINITION 46 Saffir-Simpson Hurricane Damage Potential Scale TERM 47 Seasonality DEFINITION 47 Late August to early September - peak Why? TERM 48 Tropical Cyclone Hazards DEFINITION 48 High winds tornadoes move in direction of circulation - not necessarily the normal SW - SE Strong pressure gradients produce sea level difference Water rises in response to less air above it High tide makes storm surge worse Coastal configuration is important (Bays are Worst!) TERM 49 Flooding DEFINITION 49 Depends on forward speed of hurricane Isaac had forward speed of 6 mph at landfall, over 20' of rain during the storm TERM 50 Storm Surge DEFINITION 50 By far the biggest hazard Surge can be 20-25 feet in Category 5 storms The storm pushes sea water inland TERM 51 Eye wall DEFINITION 51 the area of the most intense precipitation TERM 52 Eye DEFINITION 52 central area with clear skies Inward spiraling clouds form dense rain bands around TERM 53 Landfall DEFINITION 53 when the eye moves onshore