global wind pattern that affects how our weather systems move (US-west to east) prevailing westerlies boundary between air masses fronts a front where cold air moves in under a warm air mass cold front a front where warm air moves in over a cold air mass warm front when a cold and warm air mass meet, but neither moves stationary front when two cold air masses meet and pushes the warm air mass upward occluded front large region of the atmosphere where the air has similiar properties throughout air mass storm that brings strong winds, heavy rain, and lightning thunderstorm tropical storm that brings destructive winds and tidal surges that forms over warm, moist water hurricane circular current of air produced by warm air rising and cool air falling convection cell small storm that forms funnel clouds of powerful winds tornado More weather vocabulary