Weather Effects

1. Weather Effects Howard Middle School 6th grade Earth Science

2. Floods • Floods can happen at any time, anywhere. • What causes floods? • Single heavy rainfalls • Days of moderate levels of rain • Melting of snow and ice • The breaking of a dam or levee • Ocean waves arriving onshore

3. Floods • Large-scale flooding often occurs during seasons with exceptionally high rainfall. • Or springtimes that produce large snowmelt. • Dams and levees are built along waterways to prevent such events.

4. Floods • Floods that result from short periods of extremely heavy rain are known as flash floods. • One common place for flash floods is the desert.

5. Hurricanes • A hurricane is a severe tropical storm, and those that hit the U.S. typically originate in the Caribbean Sea, the Gulf of Mexico, or the Atlantic Ocean. Hurricane Katrina

6. Hurricanes • In other parts of the world, hurricanes are also known as tropical cyclones and typhoons. • Hurricanes form in areas of warm tropical water where there is moisture and an absence of strong winds.

7. Formation of a Hurricane

8. Hurricanes • Hurricanes can produce high winds, heavy rains, and flooding. • In the U.S., hurricane season runs from June – November.

9. Hurricanes • Hurricanes have winds of at least 74 miles per hour that swirl around a clam center, known as the eye.

10. Hurricanes • The eye is usually about 20-30 miles in diameter, while the entire diameter of the hurricane may extend to 400 miles.

11. Hurricanes • The Saffir-Simpson Hurricane Scale classifies hurricanes into categories based on their wind speed, from a category one (less than 95 mi/hr) to a category five (more than 155 mi/hr).

12. Hurricanes • Hurricanes are low-pressure events. • Along ocean fronts, this low pressure can create a storm surge that brings large amounts of ocean water onshore, with waves reaching up to several meters high.

13. Hurricanes • Storm surges cause significant damage during strong hurricanes, due to the large amount of water and flooding.

14. Hurricanes are given names in alphabetical order (excluding letters Q, U, and Z) with the name of the first one each year starting with the letter A.

15. Hurricanes • The World Meteorological Organization rotates six lists of names and reuses names every sixth year. The name of a particularly deadly or costly hurricane is retired from the lists, and a new name is selected to take its place.

16. Tornadoes • A tornado is a violently rotating column of air that is in contact with both the ground and a cloud layer. • It is usually seen as a funnel cloud and can have winds as strong as 300 mi/hr.

17. Tornadoes • Meteorologists use the Fujita-Pearson scale to rate the severity of tornadoes based on resulting damage and assumed wind speeds. • F-0 – less than 73 mi/hr to • F-5 – 261-318 mi/hr

18. Tornadoes • A tornado’s high winds and low pressure can cause the windows of buildings to blow outward.

19. Tornadoes • Compared to any other country, the U.S. experiences the greatest number of tornadoes. • About 1,000 tornadoes are reported here per year on average, resulting in approx. 80 deaths and more than 1,500 injuries.

20. Tornadoes • Many of these tornadoes occur in “Tornado Alley,” a region of the central U.S. that includes Texas, Oklahoma, Kansas, Nebraska, and S. Dakota. • Tornadoes can form at any time of the year, but are most common between March – August.