Tornadoes Tstorms

Tornadoes Tstorms - Thunderstorms and Tornadoes Severe...

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Thunderstorms and Tornadoes Severe Thunderstorms Rapid uplift of moisture and energy è instabilities in lower atmosphere. Thermal contrasts essential Warm air trapped below cold air wants to rise rapidly, forming instability. Moisture in air è cloud condensation; water adheres to particles, falls as rain Thermal Uplift Thunderstorms Heating in valley causes thermal contrast with cooler air over adjacent mountains Especially characteristic of mountains in western U.S., also caused by thermal uplift in eastern U.S. Storms local in nature, associated with individual mountains or parts of mountain ranges. Mechanical Uplift Mechanism Frontal contrasts in temperature and moisture content in air masses Cold front Warm air trapped under cold as front advances. Instability as warm air tries to rise through cold lid Warm front Warm air rises over cold As warm air rises, unable to retain moisture as it cools Generally less vigorous trigger than cold front More on Thunderstorms Can be triggered anywhere along front May extend hundreds of km along its length Strongest contrasts in spring and summer Temperature differences between south and north, moisture drawn up from south
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Tornadoes Tstorms - Thunderstorms and Tornadoes Severe...

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