Presentation on theme: "Section 12.1 – The Causes of Weather 8 th Grade Earth and Space Science Class Notes."— Presentation transcript:
Section 12.1 – The Causes of Weather 8 th Grade Earth and Space Science Class Notes
What is Meteorology? Study of atmospheric phenomena Meteorologist – scientist who studies atmospheric phenomena
Weather vs. Climate Weather – short-term variations in atmospheric phenomena Climate – long-term, average variations in atmospheric phenomena – Determined by 30 year averages
Heating 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.
Imbalanced Heating Earth’s axis is tilted to different parts of the Earth receive different amount of sunlight at different times of the year.
Imbalanced Heating The Earth is a sphere so different places on Earth are at different angles to the sun. – Some places receive more direct, concentrated sunlight
Thermal 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.
Air Masses Air mass – large volume of air with the same characteristics Source region – area over which an air mass forms
Types of Air Masses
Tropical Air Masses Maritime tropical – form over tropical bodies of water – In the summer they bring hot, humid weather to the eastern 2/3 of North America Continental tropical – form over the southwestern US and Mexico
Polar Air Masses Maritime polar air masses – form over the North Atlantic and North Pacific Continental polar air masses – form over the interior of Canada and Alaska
Arctic Air Masses Form over regions north of 60 latitude in Siberia and the Arctic Basin During part of the winter these areas receive almost no solar radiation and become extremely cold!
Air Mass Modification Air 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.
Air Mass Characteristics Air Mass TypeWeather Map Symbol Source RegionWinter Characteristics Summer Characteristics ArcticASiberia, Arctic Basin Bitter cold, dryCold, dry Continental polar cPInteriors of Canada and Alaska Very cold, dryCold, dry Continental tropical cTSouthwest US, Mexico Warm, dryHot, dry Maritime polarmPNorth PacificMild, humid North AtlanticCold, humid Maritime tropical mTGulf of Mexico, Caribbean Sea, tropical and subtropical Atlantic and Pacific Ocean Warm, humidHot, humid