Chapter 3

Weather Patterns

Section 2

Storms

What Is A Storm?

• A storm is a violent disturbance in the atmosphere.

Thunderstorms

• Thunderstorms are heavy rainstorms with thunder and lightning.

Lightning

• During a thunderstorm, positive and negative charges build up.

• Lightning is a sudden spark, or discharge, of these charges in one of 3 ways:•Within one cloud• From cloud to cloud• From cloud to ground

Tornadoes

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

How Tornadoes Form

• Tornadoes develop in low, heavy, cumulonimbus clouds – the same clouds that bring thunderstorms.• Most likely to occur in spring and

early summer, usually found in the middle of the U.S.

Hurricanes

• A hurricane is a tropical storm with winds of 119 km/h or higher.

• In the Pacific ocean, hurricanes are called typhoons.

How Hurricanes Form

• A hurricane begins over warm water as a low-pressure area, or tropical disturbance.• If it grows in size and strength, it will

become a tropical storm, which may then become a hurricane.

How Hurricanes Form

• A hurricane gets its energy from warm, humid air.• The southern Atlantic Ocean and the

Gulf of Mexico provide the heat and moisture needed to feed a very large hurricane.

The Eye of the Hurricane

• The center of the hurricane is a ring of clouds surrounding a quiet “eye.”• The winds get stronger as you get

closer to the eye, but once you are in the eye, it calms down suddenly.

Hurricane Damage• One of the most dangerous features

of a hurricane is the storm surge.• A storm surge is a “dome” of water

that sweeps across the coast where the hurricane lands.

Lake-Effect Snow

• When a continental polar air mass (cold and dry) crosses a body of water, it picks up moisture and gets a bit warmer.

• This warm air rises, cools, condenses, and falls back down as snow.

Lake Effect Snow