ES 5.4 PPT

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5.4 THE ATMOSPHERE AND THE ENVIRONMENT

Transcript of ES 5.4 PPT

  • 1. A boom of thunder hasprobably startled you atsome point before now! The thunder was probablyan introduction to anupcoming thunderstorm. Example of severeweather, any weather capableof causing propertydamage, injury, and evendeath.

2. Small, intense weather systems producing strongwinds, heavy rain, lightning, and thunder are known asthunderstorms. 2 conditions necessary for development: Warm, moist air near Earths surface Unstable atmosphere All surrounding air is colder than the rising air mass. The air masscontinues to rise as long as surrounding air is colder. 3 stages of development include: Cumulus (strong updrafts build the storm) Mature (heavy precipitation, cool downdrafts) Dissipating (warm updrafts disappear, light precipitation) 3. Rising warm air reaches its dewpoint, condensing and forming cumulusclouds. If the atmosphere is very unstable, thewarm air will continue to rise. Grow into a dark, cumulonimbus cloud with apotential height of over 15 km. In order for a thunderstorm to beconsidered severe, it must produce one ormore of the following conditions:High winds Hail Flash floods Tornadoes 4. Thunderstorms are electrically active. Lightning is an electric discharge occurring between apositively charged area and a negatively charged area. When lightning strikes, energy is released andtransferred to the air causing the air to expand andsend out sound waves. Thunder is the sound resulting from the rapid expansion of airalong the lightning strike. Can happen in 3 ways: Between 2 clouds Between cloud and Earth Within the same cloud 5. A destructive, rotating column ofair having high wind speeds, lowcentral pressure, and contact withthe ground is known as a tornado. Happen in only 1% of allthunderstorms. Starts out as a funnel cloud pokingthrough the bottom of acumulonimbus cloud. The funnel cloud becomes a tornadowhen it makes contact with the Earthssurface. 6. A large rotating tropical weather system havingwind speed of at least 120 km/hr (75 mph) isknown as a hurricane. They are the most powerfulstorms on Earth. Can have different names: Typhoons (western Pacific ocean) Cyclones (over Indian ocean) Most form between 5 and 20 latitude in thenorthern and southern hemispheres. 7. Begin as groups of thunderstorms move over tropicalocean waters. Hurricanes are fueled through the warm ocean waterand moisture is added to the warm air throughevaporation. The warm air rises, condenses and releases large amounts ofenergy. Continue to grow as long as it is over its source ofwarm, moist air. Colder areas or land will cause the storm to die since it has lostits energy source. 8. Thunderstorm safety: Stay away from trees (possibility of lightning strike). Stay away from bodies of water. Tornado safety: Find shelter in a basement or shelter. Go to a windowless room in the center of a building. Hurricane safety: Stay updated through your TV or radio station. Evacuate if near shore. Have disaster supply kit ready.