Presentation on theme: "Section 12.1 – The Causes of Weather"— Presentation transcript:
1Section 12.1 – The Causes of Weather 8th Grade Earth and Space ScienceClass Notes
2What is Meteorology? Study of atmospheric phenomena Meteorologist – scientist who studies atmospheric phenomena
3Weather vs. ClimateWeather – short-term variations in atmospheric phenomenaClimate – long-term,average variations inatmospheric phenomenaDetermined by 30 yearaverages
4Heating the Earth’s Surface Solar radiation is constantly heating some portion of the Earth’s surface.The way solar radiation is distributed ultimately determines weather.
5Imbalanced HeatingEarth’s axis is tilted to different parts of the Earth receive different amount of sunlight at different times of the year.
6Imbalanced HeatingThe Earth is a sphere so different places on Earth are at different angles to the sun.Some places receive more direct, concentrated sunlight
7Thermal Energy Redistribution Air and water are constantly moving among the Earth’s surfaces, oceans, and atmosphere.This constant circulation keeps the same average temperatures in a particular area over time.
8Air MassesAir mass – large volume of air with the same characteristicsSource region – area over which an air mass forms
10Tropical Air MassesMaritime tropical – form over tropical bodies of waterIn the summer they bring hot, humid weather to the eastern 2/3 of North AmericaContinental tropical –form over the southwesternUS and Mexico
11Polar Air MassesMaritime polar air masses – form over the North Atlantic and North PacificContinental polar air masses – form over the interior of Canada andAlaska
12Arctic Air MassesForm over regions north of 60 latitude in Siberia and the Arctic BasinDuring part of the winter these areas receive almost no solar radiation and become extremely cold!
13Air Mass ModificationAir masses move and as they move they transfer thermal energy.As energy is transferred, the air masses characteristics change as they exchange thermal energy and moisture with the area they travel over.
14Air Mass Characteristics Air Mass TypeWeather Map SymbolSource RegionWinter CharacteristicsSummer CharacteristicsArcticASiberia, Arctic BasinBitter cold, dryCold, dryContinental polarcPInteriors of Canada and AlaskaVery cold, dryContinental tropicalcTSouthwest US, MexicoWarm, dryHot, dryMaritime polarmPNorth PacificMild, humidNorth AtlanticCold, humidMaritime tropicalmTGulf of Mexico, Caribbean Sea, tropical and subtropical Atlantic and Pacific OceanWarm, humidHot, humid