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Learn about how the atmosphere exerts pressure, influences global winds, Jetstreams, high and low-pressure systems, Coriolis Effect, air masses, weather fronts, thunderstorms, downdrafts, squalls, downbursts, tornadoes, and hurricanes. Gain insights into fascinating weather phenomena with this comprehensive guide!
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Ch 17 Section 2 Weather
Atmospheric pressure • Atmosphere presses down on you with the equivalent to one kilogram per square centimeter. • Pressure is caused by gas molecules colliding with each other and your skin. • Pressure decrease as altitude increases • Air is thinner in upper atmosphere • Oxygen decreases as altitude increases • Air planes are pressurized due to this decrease
Global winds and pressure systems • Weather patterns result from complex global patterns of wind and pressure. • Westerlies- winds that blow from the west in the middle latitudes • Tradewinds blow from the east in the tropics
Jetstreams • Jetstreams control many weather processes, such as storm development. • 12 km above surface • Can travel 500km/h • Moves north and south with seasons
High and Low pressure systems • Subtropical Highs are relatively stable belts of high pressure near latitudes of 30°.
Coriolis Effect • When air rises with low pressure and sinks with high pressure systems.
Air Masses and Weather Fronts • Air masses can be polar or tropical and continental or maritime. • Air masses interact in zones called weather fronts. • Warm and cold fronts create different types of precipitation.
Thunderstorms • A cumulonimbus cloud can have ice crystals at the top of the cloud can sometimes form hail.
Downdrafts and Squalls • The falling rain can sometimes bring cool air with it; the sinking air current is called a downdraft. • When a downdraft hits the earth’s surface and spreads out as windy gusts; it is called a squall.
Downbursts • When downdrafts hit the surface and spread out very violently. • Wind can reach speeds of 260 km/h
Tornadoes • Intense, short-lived, violent, localized storms that occur in the mid latitudes.
Tornadoes • Can move at speeds of 50 km/h across surface • Wind speeds in funnel can reach 400 km/h
Hurricanes • Tropical storms that cover vast areas and last for days • At 118 km/h winds; tropical depression is upgraded to hurricane. • Western pacific hurricanes are called Typhoons.