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Ch 19 Air Pressure and Wind Everything
is the force exerted by the weight of air above
What is exerted upward, downward, and sideways ?
What pushes down on an object and exactly balances it pushing up on the object?
What flows from areas of higher pressure to areas of lower pressure?
sea level pressure
this standard is 1013.2 millibars
when air pressure increases, the mercury in the tube rises; invented by Torricelli
lines on a map that connect points of equal pressure
the principal cause for variations in air pressure from place to place
What is the ultimate energy source for most wind
What is the force that generates winds?
The Corolis effect, friction, and pressure gradients(differences) all influence or control what?
steep pressure gradient
produces strong winds
influences wind direction, the stronger the wind, the greater the deflection of the Corolis effect
What causes the deflection of wind due to it is strongest at the poles?
high-altitude, high-velocity"rivers" of air
low-pressure systems - N.Hemisphere
winds blow counterclockwise toward the center
low-pressure systems - S. Hemisphere
winds blow clockwise toward the center.
general movement across the US is from west to east
Northern Hemisphere - the winds blow clockwise outward from the center
Air subsides in the center of this
What is associated with descending air, clear weather, & relatively dry conditions
continuous pressure belt
located in the Southern Hemisphere because there are no landmasses to interrupt that pressure belt
centers of low pressure
value of the isobars increase from the outside toward the center
causes a net flow of air inward around a cyclone and outward around an anticyclone
seasonal changes in wind direction associated with large landmasses and adjacent water bodies; occur during summer in India
an example of this is the deserts of the Sahara and the deserts of Australia
a pressure zone associated with rising air near the equator
are labeled according to the direction from which they blow
caused by topographical or variations in surface composition in the immediate area
generated because the warmer air on the mountains is less dense and glides up along the slope generating a breeze
examples of local winds; after sunset in mountainous areas, cold air moves downslope into the valley
usually originates during the day and flows toward the land
What is most intense during mid to late afternoon ?
usually originates during the evening and flows toward the water
winds that consistently blow more often from one direction than from any other
move weather across the US from west to east
instrument that is used to measure wind speed
phenomenon associated with surface temperatures in the eastern Pacific that are colder than average
phenomenon associated with surface temperature in the eastern Pacific that are warmer than average
Closely spaced "what" indicate high winds?
Widely spaced "what" indicates light winds
What deflects all free- moving objects to the right of their path of motion in the Northern Hemisphere?
If the Earth didn't rotate then the air at the equator would rise and move toward the poles. What is this called?
Where does the land heat up more during the daylight hours than does the adjacent body of water?
In coastal areas during the summer
What can impact the fishing industry, climate and the farming industry?
What is the opposite of El Nino
What happens at irregular intervals of 3 to 7 years?
What is the weather that accompanies a drop in barometric pressure?
What is the weather that accompanies a rise in barometric pressure
What causes wind?
Wind is the result of horizontal differences in air pressure. Air flows from areas of higher pressure to areas of lower pressure.
What is the energy source for most wind?
What generates pressure differences?
the unequal heating of the Earth's surface
What are the factors that control wind?
pressure differences, the Corolis effect, and friction
What are isobars?
are lines on a map that connect places of equal air pressure.
What does the spacing of isobars indicate?
it shows the amount of pressure change occurring over a given distance
A steep pressure gradient causes what?
a greater acceleration of a parcel of air
What do closely spaced isobars indicate?
that there is a steep pressure gradient and high winds
What do widely spaced isobars indicate?
that there is a weal pressure gradient and light winds
What is the driving force of wind?
the pressure gradient, which has both magnitude and direction
What does friction affect?
Wind speed and direction
What does the Coriolis effect affect?
Wind direction only
the force exerted by the weight of the column of air above a given point
an instrument that measures barometric pressure
the amount of pressure change occurring over a given distance
the apparent deflective force of Earth's rotation on all free-moving objects, including the atmosphere and oceans; Deflection is to the right in the N. Hemisphere and to the left in the S. Hemisphere
swift (12-240 km/hr), high altitude winds
a low-pressure center characterized by a counterclockwise flow of air in the Northern Hemisphere
a high-pressure center characterized by a clockwise flow of air in the Northern Hamisphere
the dominant west-to-east motion of the atmosphere that characterizes the regions on the poleward side of the subtropical highs
a wind that consistently blows from one direction more than from another
an instrument used to determine wind speed
the name given to the periodic warming of the ocean that occurs in the central and Eastern Pacific; A major El Nino episode can cause extreme weather in many parts of the world
two belts of winds that blow almost constantly from easterly directions and are located on the north and south side of the subtropical highs
in the global pattern of prevailing winds that blow from the polar high toward the subpolar low; These winds, however, should not be thought of as persistent winds, such as trade winds
the stormy frontal zone separating cold air masses of polar origin from warm air masses of tropical origin
seasonal reversal of wind direction associated with large continents, especially Asia; In winter, the wind blows from land to sea.In summer, the wind blows from sea to land