Name________________________________ Blcok:_________ Forecasting Notes Climate o An area’s long-term pattern of weather (30 years) o Controlled by latitude, elevation, nearby water, Ocean currents, topography, prevailing winds, and vegetation Weather o It’s what’s happening outside now! o It’s a result of humidity, pressure, and condensation o Energy transfer: Energy transfer among sun, atmosphere & Earth’s surface produces weather If more energy comes in than leaves, Earth’s temperature will increase If more energy leaves than comes in, Earth’s temperature will decrease Air Pressure: measured with a barometer o Changes because of elevation, temperature, and humidity o Isobar: a line that joins points with the same air pressure; lines closer together mean steeper pressure gradient Elevation: As elevation increases, the pressure decreases since there is less air around you Temperature: As temperature increases, decreases because the molecules are further apart. A warm air mass has low pressure & rises A cold air mass has high pressure & sinks Warm air rises WINDS: Air flows from high pressure to low pressure, forming winds. H= High pressure L= Low pressure Cold air sinks Winds (Continued) o Air over land cools faster & heats faster than air over water. o Sea breeze: when winds blow inland from the ocean, because a warm low pressure area is over the land o Land breeze: when winds blow off the land to the ocean because a warm low pressure area is over the ocean Factors Affecting Winds: Coriolis effect Hurricanes in the Northern Hemisphere rotate counterclockwise while hurricanes in the Southern Hemisphere rotate clockwise. Coriolis effect: the tendency of an object moving freely over Earth’s surface to curve away from its path of travel, caused by E’s rotation. and Jet Stream: a band of swiftly moving wind, moving from East to West, at the top of the troposphere, unaffected by friction Global Wind Patterns: o o Intertropical convergence Zone(ITCZ): low-pressure zone near equator caused by warm, rising air Trade winds: 5-20° latitudes - warm & steady winds o o Sub-Tropical highs: 20-35° latitudes - air usually sinks - very dry w/ little wind - deserts Polar highs: high pressure regions near the poles (sinking air) - very dry Seasonal Winds: Summer: land hotter than ocean, so blows moist air inland Summer monsoon: winds and rain Winter: ocean hotter than land, so blows dry air to sea Winter monsoon: winds and no rain Temperature Maps o are colored to show… temperatures o Isotherms: lines that connect places with the same temperature Air Mass: A large body of air in the lower troposphere that has similar characteristics throughout Temperature & humidity depend on origin and move with the air mass Types of Air Masses Continental polar (cP): cold and dry Maritime polar (mP): cold and wet Continental tropical (cT): warm and dry Maritime tropical (mT): warm and wet Fronts: boundary between two air masses Cold Front: boundary between advancing cold air mass & a warmer air mass it is displacing Rising warm air usually produces precipitation if wet Air becomes colder after front passes Warm Front: boundary between advancing hot air mass & a colder air mass it is displacing 1st clouds days in advance, then RAIN Air becomes warmer after front passes Occluded : when cold front ‘catches up’ to a warm front, producing clouds& precipitation Stationary: when a front stops moving forward, producing clouds & precipitation – causes floods if stationary too long Locating a Front: o Wind direction changes o Temperature changes sharply o Dew Point changes sharply Forecasting: Computer models take current data & plug it into equations to predict weather Meteorologists take computer models & tweak them to fit their experience with local conditions Trend Method: using past movement of a front & precipitation to predict future movement