Chapter 7 Study Guide

scales of motion

Different levels of atmospheric movement, including Microscale, Mesoscale, Synoptic scale, and Global scale.

Microscale

The smallest scale of atmospheric motions.

Mesoscale

Meteorological phenomena ranging from a few km to about 100 km, including local winds and thunderstorms.

synoptic scale

Typical weather map scale showing features like high- and low-pressure areas over a continent.

global scale

The largest scale of atmospheric motion, also known as the planetary scale.

Macroscale

Meteorological synoptic scale that covers areas from the size of a continent to the entire globe.

rotor

Turbulent eddies formed downwind of a mountain chain, causing hazardous flying conditions.

wind shear

The rate of change of wind speed or direction over a given distance.

clear air turbulence (CAT)

Turbulence encountered by aircraft in cloudless skies, influenced by thermals, wind shear, and jet streams.

thermal circulation

Air flow mainly resulting from temperature differences, creating areas of high and low pressure.

sea breeze

A local wind that blows from the ocean onto land, caused by temperature differences.

land breeze

A coastal breeze blowing from land to sea, usually occurring at night.

valley breeze

A wind system in a mountain valley that blows downhill at night and uphill during the day.

mountain breeze

A local wind in a mountain valley that blows downhill at night.

katabatic wind

Any wind blowing downslope, usually cold.

chinook wind

A warm, dry wind on the eastern slopes of the Rocky Mountains.

Santa Ana wind

A warm, dry wind from the east in Southern California, derived from compressional heating.

Haboob

A dust or sandstorm formed by cold downdrafts from a thunderstorm lifting dust into the air.

dust devils

Small, rapidly rotating winds visible by the dust and debris they lift; most common on hot afternoons.

Monsoon

Seasonal winds that shift direction during different times of the year, often bringing heavy rainfall.

Hadley cell

A thermal circulation model explaining trade winds, characterized by rising air near the equator.

Doldrums

A low-pressure region near the equator with light, shifting winds.

subtropical highs

Semipermanent high-pressure areas centered around 30° latitude.

trade winds

Winds in the tropics blowing from the subtropical highs to the equatorial low.

intertropical convergence zone (ITCZ)

The boundary where the trade winds of the Northern and Southern Hemispheres meet.

Westerlies

Westerly winds that blow in the middle latitudes on the poleward side of subtropical high-pressure areas.

polar front

A semi-permanent front separating tropical air masses from polar air masses.

subpolar low

A belt of low pressure located between 50° and 70° latitude.

polar easterlies

Easterly winds located at high latitudes poleward of the subpolar low.

Bermuda high

A semipermanent high-pressure area located over the Atlantic Ocean near 30° latitude.

Pacific high

A semipermanent high-pressure area located off the western coast of North America.

Icelandic low

A subpolar low-pressure area centered near Iceland.

Aleutian low

A subpolar low-pressure area centered near the Aleutian Islands.

jet stream

Strong winds concentrated within a narrow band in the atmosphere.

subtropical jet stream

The jet stream found between 20 and 30° latitude, typically at altitudes of 12 to 14 km.

polar front jet stream

The jet stream associated with the polar front in middle and high latitudes.

Gulf Stream

A warm, swift, narrow ocean current flowing along the east coast of the United States.

Upwelling

The rising of cold water toward the surface from deeper ocean regions.

El Niño

A periodic warming of ocean surface temperatures in the central and eastern Pacific Ocean.

Southern Oscillation

The reversal of surface air pressure at opposite ends of the tropical Pacific Ocean during El Niño.

ENSO

A semi-cyclic variation in surface air pressure across the tropical Pacific, leading to El Niño or La Niña.

La Niña

A condition characterized by cooler than normal surface waters in the central and eastern tropical Pacific.

teleconnections

Linkages between weather changes occurring in widely separated regions.

Pacific Decadal Oscillation (PDO)

A reversal in ocean surface temperatures that occurs every 20 to 30 years.

Indian Ocean Dipole (IOD)

A cyclic shift in sea surface temperatures between the western and eastern Indian Ocean.

North Atlantic Oscillation (NAO)

A reversal of atmospheric pressure over the Atlantic Ocean affecting weather in Europe and North America.

Arctic Oscillation (AO)

A reversal of atmospheric pressure over the Arctic impacting upper-level westerly winds and winter weather.

polar vortex

A semipermanent zone of upper-level low pressure found in polar regions.