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Tornadoes and Hurricanes. Tornadoes. - rapidly whirling, funnel-shaped clouds that reach down from cumulonimbus storm clouds & touch Earth usually last 10 minutes or less - from very small to a couple miles wide - Occur most often in the Spring (April – June)
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- rapidly whirling, funnel-shaped clouds that reach down from cumulonimbus storm clouds & touch Earth usually last 10 minutes or less - from very small to a couple miles wide - Occur most often in the Spring (April – June) - central portion of U.S. is called “tornado alley” as it has the best conditions for tornadoes to form WHAT ARE TORNADOES? Tornadoes are rated on the Fujita scale: F1-F5 Weakest to Strongest
Formation of a Hurricane • Hurricanes are storms that form over WARM tropical waters. The hurricanes that affect the east coast of the United States form off the west coast of Africa where the water is warm, the air is humid, and the winds converge. • Hurricanes are FUELED BY LOTS OF WARM WATER. The y need it TO FORM AND TO STAY STRONG! • NO WARM WATER = NO HURRICANE!
Tropical cyclones are areas of low pressure that develop over tropical waters. We call them tropical depressions if their wind speeds are more than 25 mph and less than 38 mph. A tropical disturbance becomes a tropical depression if it lasts more than 24 hours. Tropical Depression
A tropical depression becomes a tropical storm when its winds rise above 38mph. It is called a tropical storm if the winds are between 39 and 73 mph. Tropical Storm
A tropical storm becomes a HURRICANE when its winds reach 74 mph. Hurricanes
Category 1 – Winds between 74- 95 mph Category 2 – Winds between 96- 110 mph Category 3 – Winds between 111-130 mph Category 4 – Winds between 131-155 mph Category 5 – Winds above 156 mph Hurricane Categories
Hurricanes can be very big, even as big as the state of Ohio! They can be seen from outer space! The entire FORMATION & LIFE of a hurricane takes DAYS OR WEEKS! Because hurricanes seldom travel in straight paths, meteorologists predict several paths. Hurricanes usually LOSE POWER as they travel OVER LAND. Hurricanes destroy beaches, buildings, and vegetation. Hurricanes bring strong winds, heavy rain, storm surges, flooding, and tornadoes. Hurricane Facts
Review • Which is larger, a hurricane or a tornado? • Which moves faster, a hurricane or a tornado? • Which lasts longer? • Where do hurricanes form? • Where do tornadoes form? • What do we call the area of the US that has a high occurrence of tornadoes? • How long do tornadoes last? • How long do hurricanes last? • Name two precautions in the event of a tornado. • Name two precautions in the event of a hurricane.
TORNADOES HURRICANES BOTH