Topic/Objective: Essential Question: Full Name: Class: Period: Date: Tutor Use Only: Air Pressure and Wind (Chapter 19) Air Pressure the weight of the atmosphere pushing down on the Earth exerting a force per unit area Measuring Air Pressure Barometers measure air pressure : o Mercury o Aneroid : o inches & millimeters used in mercury readings o millibars used on weather maps Factors Affecting Air Pressure 1. o as temperature increases, air pressure decreases o molecules move farther apart 2. o as humidity increases, air pressure decreases o water vapor has less mass than air
Air Pressure on Weather Map are lines that connect areas of air pressure connected areas form and allow us to view patterns closely spaced isobars indicate rapid change Highs and Lows when air pressure is greater at the center than the outside we have a when it is lower, we have a High Pressure The Air in Highs & Lows Low Pressure
Wind moderates temperature, distributes moisture, cleanses the atmosphere Named for the in which they Created by in air pressure Blow from pressure Measuring Wing : measures wind speed in mph or kph : measures wind direction Air Pressure & Wind is the change in the air pressure divided by the distance over which the air pressure changes the greater the pressure gradient the the wind blow between two points Sea Breeze land heats up than the ocean air over land cooler, denser air from over the ocean blows in to replace rising air Land Breeze Reverses at Ocean heat from day, land heat quickly Breeze switches
Sea and Land Breezes SEA BREEZE LAND BREEZE FACTORS AFFECTING WINDS 1. The Coriolis Effect the tendency of an object moving over the Earth s surface to curve away from its path of travel caused by Earth s greater near the increases as speed on an object Noticeable for objects traveling over great (i.e. planes, winds, ocean currents) Northern hemisphere deflected to the Southern hemisphere deflected to the
The Coriolis Effect & Wind o Winds blow clockwise of a high pressure center o Wind blow counterclockwise a low pressure center o This is reverse for the Southern hemisphere 2. Friction the surface, the winds the winds, the the Coriolis Effect This means the Coriolis Effect has a lesser effect on surface winds than upper atmosphere winds (there s less friction in the upper atmosphere) 3. Time of Year [remember air flows from high to low pressure] High and Low pressure have differences varies throughout the year, base on the amount of winds change
The Jet Stream band of very strong winds in the upper troposphere thousands of kilometers long, hundreds wind and one kilometer tall polar-front jet stream controls our weather and brings cold air from the poles faster in the winter Convection Cells continuously atmosphere create global as air moves away from highs and towards lows Global Wind Patterns if the Earth did not rotate, we d have large convection cell Hot air rises at the, cools, then sinks at the and flows back down to the equator
Because the Earth does rotate the Coriolis Effect this one convection cell air cools before it reaches the poles - celled circulation model is used 3-Celled Circulation Model Circulation cells are caused by alternating and pressure bands at the surface also called Hadley cells winds deflect to the in the Northern hemisphere Intertropical Convergent Zone (ITCZ) Area where the surface winds of the two hemispheres hot, humid, to no wind present also called the Trade Winds area between and in each hemisphere winds Location where merchants wanted to sail their ships Effect of Global Wind Patterns Precipitation patterns are effected Deserts at mid-latitudes & on leeward side of mountains
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