Dr. Hooda Text Book : Pages 450 - 459 Storms Dr. Hooda Text Book : Pages 450 - 459

What is a storm? A violent disturbance in the atmosphere.

2. Cause rapid air movement What are the main steps involved in the formation of a storm? 1. Involves sudden changes in air pressure 2. Cause rapid air movement 3. Conditions that bring one kind of storm in one area often cause other kinds of storms in the same area

Types of severe storms Thunderstorm - A small storm often accompanied by heavy precipitation and frequent thunder and lightning. Tornado – A rapidly whirling, funnel-shaped cloud that reaches down from a storm cloud to touch Earth’s surface and is formed over land in the mid-latitudes. Hurricane – A tropical storm that forms over warm (80 degrees) tropical seas and has winds of about 119 kilometers per hour or higher.

Thunderstorms A thunderstorm forms when warm, humid air rises rapidly within a cumulonimbus cloud and a cold air moves downward. Increased surface moisture would increase the chance of a thunderstorm. Is often accompanied by heavy rain, lightning and thunder.

Thunderstorm Watch Thunderstorm Warning Issued by National Weather Service This means that conditions are favorable for a thunderstorm Length is multiple hours. Thunderstorm Warning Issued By Local Weather Service Means a severe storm has been spotted by dopplar radar Usually lasts for only an hour

Why do we see lightning before we hear thunder? Because light travels much faster than sound. Thunderstorm / Lightning Safety Stay indoors, away from doors and windows. Avoid objects that conducts electricity, such as metal objects and bodies of water. Do not seek shelter under the trees. Do not use phones with cords. Remember: Cars are pretty safe…

When can a tornado happen? What is a tornado? A tornado is a rapidly whirling, funnel shaped cloud that reaches down from a cloud to touch Earth’s surface. When can a tornado happen? Happen in spring and early summer, often late in the afternoon when the ground is warm. Happen late in the day, when earth’s surface is very warm, convection (the flow of heat through a material, causing hot parts to rise and cooler parts to sink) can get very strong.

What type of air masses are involved in the formation of a tornado ? Tornadoes happen where dry, cold air masses mix with moist, warm air masses.

Where does Tornadoes happen? More tornadoes occur in the United States than in any other country, especially in the area known as TORNADO ALLEY. Tornado Alley About 800 tornadoes every year in the United States.

How are tornadoes formed?

Tornado Happenings in Tornado Alley A warm, humid air mass moves north from the Gulf of Mexico into the lower great Plains. A cold, dry air mass moves south from Canada. When the air masses meet, the cold air moves under the warm air, forcing it to rise. A storm line, or narrow band of thunderstorms, is likely to form, with storms traveling from southwest to northeast. A single storm line can produce ten or more tornadoes.

Tornado Watch Tornado Warning Tornadoes Safety A tornado has formed. Conditions are favorable for a tornado to form Tornado Warning A tornado has formed. Tornadoes Safety The safest place to take a shelter is in a storm shelter or the basement of a well-built building. http://environment.nationalgeographic.com/environment/natural-disasters/forces-of-nature/

On June 3, 1980, a series of tornadoes devastated the city of Grand Island, Nebraska. Seven tornadoes hit within a three hour period. The storm did massive damage and closed the city down for three days.

Hurricanes

What is a hurricane? Where does it form? How long does it last? A tropical storm that forms over warm (80 degrees) tropical seas and has winds of about 119 kilometers per hour or higher. Hurricanes form over warm tropical (7 – 15 degrees latitude) seas, Atlantic, Pacific, and Indian Oceans In the western Pacific Oceans, hurricanes are called typhoons. Storm usually doesn’t last for more than 7-10 days. As it moves inland it continues to move across the land but it begins to weaken Where does it form? How long does it last?

Formation Regions When does it happen? Late summer and Fall between (between July and October). Formation Regions

How Hurricanes Form 1. Begins as a low-pressure area over warm water, or a tropical disturbance. 2. Warm, humid air rises and begins to spiral. 3. As air rises, more warm, moist air is drawn into the system and the hurricane gains energy. 4. As winds spiral inward, bands of high winds and heavy rains form.

How Hurricanes Move In a hurricane, air moves rapidly around a low-pressure area called the eye. There is a calm air inside the eye of a hurricane. In the Atlantic ocean, hurricanes are steered by trade winds toward the Caribbean islands and southeastern United Stares.

Map Symbols

Typical Path

Naming System Hurricane Watch Hurricane Warning A list of names from A-W (excluding Q) Alternate from male to female 6 lists, repeated in cycle Big name storms retired, like KATRINA. Hurricane Watch A hurricane poses a possible threat within the next 36 hours Hurricane Warning Hurricane conditions expected within 24 hours

Hurricane Safety IF you choose to stay…. Best plan is to evacuate Towns have voluntary evacuation during a watch, and some switch to mandatory during a warning. Plan early in advance IF you choose to stay…. Board all windows Prepare Flashlights, avoid candles Stay tuned to radio Stay indoors http://environment.nationalgeographic.com/environment/natural-disasters/forces-of-nature/

The Saffir-Simpson Scale http://www.nhc.noaa.gov/aboutsshws.php Saffir-Simpson Wind Scale and Animations   http://www.nhc.noaa.gov/surge/ Storm Surge Overview and Animations Scale developed to categorize the hurricane based on wind’s speed. If a storm has sustained winds speed below 74 mph, then the storm is called a Tropical Storm.