27. wind vane – instrument used to measure wind direction28. anemometer – instrument used to measure wind speed29. local winds – winds that blow over short distances30. sea breeze – the flow of cooler air from over an ocean or lake toward land31. land breeze – the flow of air from land to a body of water32. global winds – winds that blow steadily from specific directions over long distances33. Coriolis effect – the change that Earth’s rotation causes in the motion of objects and explainshow winds curve34. trade winds – a wind blowing almost continually toward the equator from the northeast in thebelt between the northern horse latitudes and the doldrums and from the southeast in the beltbetween the southern horse latitudes and the doldrums35. doldrums – regions near the equator with little or no wind36. horse latitudes – calm areas of falling air located at 30 degrees north and south of the equator.37. prevailing westerlies – blow away from the horse latitudes. The prevailing westerlies in theNorthern Hemisphere are responsible for many of the weather movements across the UnitedStates and Canada.38. polar easterlies – these winds begin in the east and blow cold air away from the poles39. jet stream – bands of high-speed winds that generally blow from west to east, wandering aroundthe Earth north and south along a wavy path, located about 10km above the Earth’s surface.40. air mass – a huge body of air that has similar temperature, humidity and air pressure at anygiven height41. front – the boundary where unlike air masses meet, but do not mix. There are 4 types: cold,warm stationary and occluded42. dew point – the temperature at which condensation begins43. relative humidity – the amount of water vapor in a given volume of air44. cumulus – fluffy white clouds, usually with flat bottoms, that look like rounded piles of cotton45. cirrus – wispy, feathery clouds made mostly of ice crystals that form at high levels46. stratus – clouds that form in flat layers and often cover much of the sky47. cumulonimbus – type of cumulus cloud. “nimbus” refers to water. Tops are shaped like an anviland are often referred to as thunderheads because they can bring heavy rain, lightning andthunder48. cyclone – a swirling center of low air pressure, marked with an L on a weather map. In theNorthern Hemisphere, the winds in a cyclone spin counterclockwise. Low pressure areas oftenbring clouds and precipitation.49. anticyclone – high pressure centers of dry air, marked with a H on a weather map. Wnds in ananticyclone spin clockwise in the Northern Hemisphere. High pressure areas usually have dry,clear weather.50. storm – violent disturbance in the atmosphere involving change in air pressure causing rapid airmovements.51. thunderstorm – a small storm often accompanied by heavy precipitation and frequent thunderand lightning that form in large cumulonimbus clouds.52. lightning – a sudden spark, or electrical discharge, as positive and negative charges jumpbetween parts of a cloud, between nearby clouds, or between a cloud and the ground.