Chapter 6 Flashcards
Air pressure
the force exerted by the weight of a column of air above a particular location
Average sea-level pressure
serves as the division between what we call “high pressure” and “low pressure” at the surface
High pressure
values greater than 1013.2 mb
Low pressure
below 1013.2 mb
Wind
nothing more than the movement of air molecules from one place to the next
Pressure gradient
The spacing of isobars indicates the change in pressure over distance
Coriolis effect
a mass moving in a rotating system experiences a force acting perpendicular to the direction of motion and to the axis of
rotation
Friction
The friction imposed on air mechanically slows the wind and diverts its direction.
Cyclone
areas of low pressure
Anticyclone
areas of high pressure that exhibit nearly circular isobars
Convergence
moving towards a point/area
Divergence
moving away from a point/area
Intertropical convergence zone
The Equatorial trough
Subtropical high pressure
Upper air convergence and radiational cooling cause the air to subside in the subtropics. As the air reaches the surface,
atmospheric pressure increases forming the subtropical highs
Subpolar low pressure
The polar easterlies collide with the westerly wind belt at about 60 N and S creating a broad belt of low pressure
Polar high
dome of high pressure created by loss of energy at the poles
Northeast tradewinds
the pressure gradient between the high at 30 N and the low over the equator
Westerlies
wind belt
Polar easterlies
Air moving equatorward is turned in an easterly direction
Monsoon
wind that changes direction with season
Land/Sea breeze
created along coasts where land and water create variations in pressure due to differences in the way these two bodies
heat and cool.
Chinook
a warm dry wind on the leeward side of a mountain
Mountain/Valley wind
During the daytime, mountain slopes warm causing the air over the slope to be warmer than the air over the valley at the
same elevation. Warming the air causes it to rise upwards creating a valley wind. During the evening, the air chills due
to a loss of surface energy to space. The cool dense air moves down slope as a mountain wind.
Santa Ana wind
warm and dry wind.
Upper-level westerlies
the upper troposphere poleward of 15 to 20 latitude there is an average westerly flow
Upper-level easterlies
Between 15 - 20 north and south latitude; considered to be an extension of the trade winds
Jet Stream
a high speed corridor of air responsible for creating and moving large pressure systems through the midlatitudes
Circumpolar vortex
The subsidence creates a vast area of low pressure aloft
Meridonal flow
transfer of cold air toward the south and warm air toward the north
Zonal Flow
edge is flatter, running more west to east in direction
Warm ocean current
corridors of warm water moving from the tropics poleward where they release energy to the air.
Cold ocean current
corridors of cold water moving from higher latitudes toward the equator
El Niño
weakening of the trade winds in the central and western Pacific allows warm water to invade the eastern Pacific. Along
the Peruvian coast, the encroaching warm water displaces the nutrient-rich north-flowing cold ocean current causing a
decline in fisheries. Today, the phenomenon is known as the “ El Niño/Southern Oscillation”
La Niña
Cooler than normal ocean temperature in the eastern pacific/Peruvian Coaast region is called “La Niña”
