2 ThunderstormsSmall intense systems that can produce strong winds, rain, lightning and thunder.Need 2 conditionsAir near surface needs to be warm and moistThe atmosphere must be unstable
3 Becoming unstable…The surrounding air is colder than the rising air massThis makes that rising air CONTINUE risingThe thunderstorm occurs when the air is rising rapidlyForms cumulonimbus cloud
4 Lightning!Electrical charges build up near the tops and bottoms of clouds heading from positive to negative to positive (opposites attract)Flash of light occurs when a charge sparksThe flash heats the air to about the temperature of the surface of the sunENERGY IS RELEASED
5 More… Thunderstorms get their energy from humid air Can produce high winds, flood, or tornadoes
6 Effects Thunderstorms can have positive or negative effects Positive – rain can provide water for crops and restore lakes and streamsNegativeFlash floodsWindsHailLightning
7 Funnel CloudWind traveling in 2 different directions causes it to start spinningThe updrafts of air push the spinning column down, sometimes to the groundIt is called a tornado once it hits the groundFunnel cloud Tornado
8 Tornadoes Cumulonimbus clouds can sometimes form tornadoes Only 1 percent of thunderstorms form tornadoes
9 Formation About 75 percent of tornadoes happen in the United States. Warm humid air comes up from the Gulf of Mexico and meets cold dry air from Canada in the plains.
11 PathA tornado moves along with its thunderstorm, it travels fast and weaves a path that is impossible to predictTornado watchWhen the weather conditions might produce tornadoes.Tornado warningWhen a tornado hasbeen detected
12 Hurricanes Most powerful storms on Earth Different names Typhoons – Pacific OceanCyclones – Indian OceanForm over warm tropical oceansVary in size and can travelthousands of miles
14 Formation of Hurricanes Hurricane Season – August to OctoberBegins as a group of thunderstormsEnergyComes from condensed water vaporFuelDirect contact with warm ocean waterHurricanes will continue to grow until they lose their source of warm, moist air
18 Winter storms produce snow and ice Winter storms are formed when two air masses collide. A continental polar air mass forming over snow is especially cold, dry, and dense. It forces moist air to rise very quickly.
19 BlizzardsA storm with falling or blowing snow, winds at least 35 mph, reduced visibility and intense cold.Occur in many parts of the Northern and Central United States.
20 Formation of a Blizzard Very similar to thunderstorms, only the air is rising even higher.Warm air has the moisture, and is pushed even higher than normal, passing through clouds that are high in the skyThose clouds take some moisture, and it freezes
21 Duration of a BlizzardFor a storm to be considered a blizzard it has to last at least 3 hours.Some blizzards can last for a few hours or even days!
22 Dust StormStrong, violent winds that carry fine particles like silt, clay, sand and dust-filled air over an extensive area.
23 Formation of a Dust Storm Any area with a lot of dust and sand particlesNeed dry air and a lot of windHugeCan spread over hundreds of milesPowerfulWind speeds of at least 25 miles per hour (40 km)
24 Dangers of a Dust Storm Arrive without warning Create large wall of dust and debris.Last only a few minutesLeave debris behindHard to see during stormBreathing is impacted.Takes fertile top soil away and reduces future crops.Current crops are covered with dust.