STORMSSTORMS

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

atmosphere caused by sudden changes in pressure

Types of storms:– Thunderstorms– Tornadoes– Hurricanes– Blizzards

ThunderstormsThunderstorms• A thunderstorm is a

heavy rain shower that brings thunder and lightning

• Form within large cumulonimbus clouds

• Warm/humid air rises rapidly and cools forming a dense “thunderhead”

LightningLightning

• Positive and negative charges build up in storm clouds

• Lightning is a sudden energy discharge (spark) as these charges jump between parts of a cloud, between clouds, or ground

ThunderThunder

• What causes thunder?– A lightning bolt can make the air around it as

hot as the surface of the sun!– This hot air expands suddenly and explosively– The sound of this explosion is thunder

Lightning to Thunder

• After you see a bolt of lightning, you can find out how far away the lightning is by counting the seconds that pass until you hear thunder.

• It takes 4.85sec from the time you see a bolt of lightning to hear thunder-so if you see lightning and count to 10 before you hear thunder, the lighting was about 2 miles away.

TornadoesTornadoes

• A tornado is a rapidly whirling, funnel-shaped cloud that reaches down from a storm cloud to the Earth’s surface

• If it occurs over a lake or ocean is it called a water spout

TornadoesTornadoes• How do tornadoes form?

– Tornadoes come from the same clouds as thunderstorms: cumulonimbus

– Most likely to come in spring or early summer– Warm humid air moves north from the gulf,

and cold dry air moves south from Canada– When these air masses meet, the cold air

moves under the warm air, which rises, causing a line of thunderstorms

Atlanta-EF-2Atlanta-EF-2March 14, 2008

On March 14th of 2008 at 9:45pm, nature released her wrath on downtown Atlanta, Georgia. As you look at this photo and admire it’s beauty, it is easy to forget about the devastation and chaos it caused. The actual tornado is located on the far left of the photo, and if you look close you can see the debris cloud surrounding it. The EF-2 tornado was 200 yards wide and circulated with 135mph winds. I was merely at the right place at the right time watching a historical event unfold.

HurricanesHurricanes• What is a hurricane?

– A tropical storm that has winds of 119 kilometers per hour or higher

– A typical hurricane is about 600 kilometers across

• Atlantic Ocean Hurricane

• Pacific or Indian Ocean Typhoon

Watch out August, September, Watch out August, September, and Octoberand October

• How does a hurricane form?• A hurricane gets its energy from warm

humid air at the ocean’s surface

• This air rises and forms clouds, and more air is drawn into the system

• Winds spiral inward toward the area of low pressure

““We’re in the eye of the We’re in the eye of the storm”storm”

• The eye of the hurricane is a ring of clouds surrounding a quiet “eye”

• The storm worsens until it reaches the eye where it is calm and clear

• Once the eye has past the storm starts back up, but the winds blow from the opposite direction!

Eye

How a Hurricane MovesHow a Hurricane Moves

• Hurricanes usually last a week or more• Atlantic hurricanes are steered by winds

toward the Caribbean islands and southeastern US

• Once a hurricane passes over land, it no longer has warm, moist air to draw energy from

• It will gradually slow down and lose strength

Storm SurgeStorm Surge• One of the most

dangerous features of a hurricane is a storm surge

• A storm surge is where the ocean level may raise up to six meters above normal

• This water comes ashore destroying beaches and buildings along the coast

BlizzardsBlizzards

• Snow falls when humid air cools below 0°C (32°F)

• The Great Lakes send water vapor into the air bringing huge snowstorms to places like Buffalo, NY and Rochester, NY

• This is called Lake-effect snow

FloodsFloods

• Floods occur when so much water pours into a stream or river that it overflows its banks and covers the land on either side with water

• A flash flood is a sudden, violent flood that occurs within a few hours, or even minutes, of a storm