Unit 8 Vocabulary
Climatic Interactions
hurricane - a huge, slowly-spinning tropical storm that forms over water and has winds of at
least 119 km/h (74 mph).
upwelling – subsurface ocean current that brings nutrient-rich water from the ocean bottom to
the surface.
convection current – when temperature differences cause fluids to expand and move; the less
dense areas continually rise, and the more dense areas continually sink creating a cyclical
current.
atmosphere – an envelope of mixed gases are held to the Earth by gravity; the densest gases
are near the surface of the Earth.
cyclone – a storm or system of winds that rotates about a center of low atmospheric pressure
counterclockwise in the Northern Hemisphere, advances at a speed of 20 to 30 miles (30 to 50
kilometers) an hour, and often brings a great deal of rain.
jet stream – narrow stream of high-speed wind in the atmosphere, generally moving west to
east in the Northern Hemisphere.
gyres – a circular or spiral motion or form; a giant circular oceanic surface current.
Gulf Stream – warm current in the North Atlantic flowing from the Gulf of Mexico northeast
along the United States coast to Nantucket & then eastward.
humidity – amount of water vapor in the air.
psychrometer – instrument used to measure moisture in the atmosphere.
prevailing winds – mid-latitude global wind that blows mostly in one direction.
air mass – a large body of air that has about the same temperature and humidity throughout it.
air pressure – a measure of the weight of the atmosphere per unit of area on the Earth’s
surface; also called barometric pressure.
deep water currents – movement of deep water in the ocean basins by density driven forces
and gravity; the density difference is a function of different temperatures and salinity.
surface currents – ocean current flowing at the surface, caused mainly by winds.
anemometer – instrument used to measure wind speed.
weather front – a boundary separating two masses of air of different densities, and is the
principal cause of meteorological phenomena.