Transcript of Storms
Thunderstorms At any given moment, nearly 2000 thunderstorms are occurring around the world. Most do little more than provide welcome relief on a muggy summer afternoon. Some, however, grow into atmospheric monsters capable of producing hail the size of baseballs, swirling tornadoes, and surface winds of more than 160 km/h. These severe thunderstorms can also provide the energy for nature's most destructive storms: hurricanes. All thunderstorms, regardless of intensity, have certain characteristics in common. Clouds Cumulous clouds become Cumulonimbus clouds. Conditions Moisture Lift Instability Water must be present in the air to condense and release HEAT. When the water releases heat it keeps the cloud WARMER than the air around it so that it will continue to RISE. The air must continue to RISE so that the moisture can continue to CONDENSE releasing HEAT into the air. Keeping the cloud WARMER than the air will keep it rising and keep the storm UNSTABLE. The air must continue to get colder the higher you get so that it always stays COOLER than the cloud. This way the cloud will continue to RISE and grow. Air Mass All thunderstorms form when moist air rises and condenses releasing latent heat. ...what can make that happen? Form because of UNEQUAL HEATING of Earth's surface within ONE airmass. Reaches its maximum difference in temperature MID-AFTERNOON. Happens commonly in the MOUNTAINS or along COASTAL areas. Frontal storms don't depend on daytime heating to lift the warm air, so they can carry on long INTO THE NIGHT. RAIN Air rises vertically UPDRAFT takes moisture up to the top of the cloud. Moisture CONDENSES into droplets and releases HEAT. Droplets COALESCE to form bigger and bigger droplets. As the rain falls it COOLS the air around it. COOL air sinks very fast to the ground - DOWNDRAFT. DOWN DRAFTS cause gusty winds. Nearly equal UPDRAFTS & DOWNDRAFTS at this stage. Warm air is USED UP. Updraft STOPS. No more precipitation is formed. Rain SLOWS DOWN and eventually STOPS. Thunderstorms grow in 3 stages... Frontal Form because of an advancing COLD FRONT. Fronts can be HUNDREDS OF KM long with storms all along the edge. All thunderstorms are not created equal. Some die out within minutes, while others flash and thunder throughout the night. What makes one thunderstorm more severe than another? Occasionally, weather events come together in such a way that there is a continuous supply of surface moisture. This happens along a cold front that moves into warmer territory and can lift and condense a continuous supply of warm air. In this case, a line of thunderstorms can last for hours or even days as they continually regenerate themselves with the new, warm air that is introduced into the updrafts. SUPERCELL Self sustaining, extremely powerful storms characterized by intense rotating updrafts. Of the estimated 100,000 storms that occur each year in the United States, only about ten percent are considered to be severe, and fewer still reach classic supercell proportions. But when certain atmospheric conditions come together in the right way, the results can be spectacular and sometimes deadly, as you'll learn next. A lightning bolt forms when friction between the updrafts and downdrafts within a cumulonimbus cloud separates electrons from some of their atoms either in the cloud or on the ground. Lightning 30,000 C 6,000 C Hail Flooding How fast will the system move? How much moisture is the system carrying? "Of all the dangers associated with thunderstorms, the most impressive by far is a TORNADO." a violent, whirling column of air in contact with the ground. What is it called before it reaches the ground...? FUNNELFull transcript
CLOUD Fujita Tornado Intensity Scale An area that extends from
northern Texas through Oklahoma,
Kansas, and Missouri where cold continental
polar air collides with maritime tropical air forming intense supercells with fast winds. Tornado Alley How are tornadoes formed? Tropical Cyclone Large, rotating, low pressure storms. Hurricane Typhoon Cyclone How do hurricanes form...? 1. Warm Ocean Water 2. Rising Air 3. Rotation 4. Development of an EYE Ingredients for a hurricane... Anatomy of a Hurricane Winds greater than 120 km/hr around the eye create a hurricane. The calm center of a hurricane. EYE WALL The strongest winds in the hurricane concentrated in a band just outside the eye. Storm Surge Occurs when hurricane-force winds drive a mound of ocean water toward coastal areas where it washes over the land.