4.1.3 Weather Hazards

Weather Hazards

4.1.3

Objectives

Learners can:

• diagram the formation of a thunderstorm

• describe the formation of a tornado

• describe the stages in the formation of a hurricane

• explain the risks associated with extreme weather events

• air mass

• condensation

• water cycle

Prerequisite Vocab

• hurricane

• lightning

• precipitation

• tornado

New Vocab

Vocabulary

a tropical storm with powerful winds

​​hurricane

an electrical discharge that often occurs during severe storms

Lightning

water that is released from clouds in the sky; including rain, snow, sleet, hail, and freezing rain

Precipitation

a destructive weather event characterized by rotating winds

tornado

Match

Match the vocabulary word to its definition.

• condensation

• air mass

• water cycle

when a gas changes to a liquid

large volume of air

movement of water through an ecosystem

• when a gas changes to a liquid

• large volume of air

• movement of water through an ecosystem

The United States experiences between 700 and 1,000 tornadoes each year. While tornadoes have occurred in all 50 states, they are most common in Tornado Alley.

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Tornadoes

Weather is a process that involves many different factors. The sun's energy is the driving force for the weather. The sun heats Earth's surface, creating temperature variations that lead to weather systems. The air movement in the atmosphere creates wind patterns that transport heat and moisture worldwide. Water vapor in the air forms clouds and can lead to precipitation.

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Water Cycle

Extreme Weather Examples

Extreme weather events are natural occurrences that can have devastating consequences. Most extreme weather events are characterized by strong wind and precipitation. Precipitation is water that is released from clouds in the sky. Severe weather precipitation can include rain, snow, sleet, hail, and freezing rain.

Lightning is an electrical discharge that often occurs during severe storms. Lightning results from the buildup of static electricity as ice and water particles collide in the cloud. The extreme heat of lightning causes the surrounding air to rapidly expand with a tremendous explosion. The explosion creates the sound of thunder.

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thunderstorms

A tornado is a destructive weather event characterized by rotating winds. This updraft can begin forming a rotational movement, resulting in a tornado that extends down from the thunderstorm. The tornado may reach the ground, resulting in significant damage and destruction.

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Tornado

A hurricane is a tropical storm with powerful winds. Hurricanes form over warm ocean water in the tropical regions of the world. Similar to a thunderstorm, hurricanes grow from rising warm air. Over warm ocean waters, hurricanes can grow much larger than a typical thunderstorm. Hurricanes often cover areas of hundreds of miles.

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Hurricane

Draw

Draw a picture of what each of the 3 extreme weather examples looks like and label them.

Stages of a Thunderstorm

The cumulus stage is the initial development of the thunderstorm. During this stage, warm, moist air rises near Earth's surface. As the air rises, it cools, forming a cumulus cloud.

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Cumulus Stage

Cool air holds less water vapor, so the buildup of moisture will eventually fall as precipitation. During the mature stage of the thunderstorm, warm air continues to feed the storm, while cooler air and precipitation fall.

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Mature Stage

The thunderstorm is no longer fueled by rising warm air during the dissipating stage. At this stage, precipitation continues to fall until little moisture remains in the air mass.

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Dissipating Stage

Multiple Choice

Which of the following conditions is necessary for the formation of severe weather?

• high atmospheric pressure

• stable air masses

• low humidity levels

• atmospheric instability

Hurricane Development

A tropical disturbance is a buildup of rain clouds over tropical waters. This formation is similar to the development of a typical thunderstorm, as warm water vapor rises and condenses into clouds.

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Tropical Disturbance

Winds blow in a circular pattern as a tropical disturbance transitions to a tropical depression. Clouds continue to build, and winds will reach up to 38 miles per hour.

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Tropical Depression

Once wind speeds reach 39 miles per hour, a tropical depression is considered a tropical storm. A tropical storm has also developed a well-defined circular shape. Warm ocean waters will continue to allow the storm to grow.

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Tropical Storm

A tropical storm will be classified as a hurricane, as wind speeds reach 75 miles per hour. By this point, the storm has developed the characteristic cyclone shape with a well-developed central point called the eye.

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Hurricane

Impacts of weather Hazards

Severe storms can produce strong winds. Winds can cause damage to homes, buildings, trees, and other structures. High winds can also lead to power outages and disrupt transportation.

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Wind

Heavy rainfall can lead to flooding and landslides. Some forms of precipitation, such as hail, can damage property. Heavy precipitation disrupts transportation and communication.

Precipitation

Severe storms can produce lightning, which can threaten people outdoors. Lightning strikes can cause injuries or fatalities. They can also start fires.

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Lightning

Coastal storms can produce storm surges. Storm surges are large waves and rising water levels that can cause flooding. Hurricanes are usually accompanied by damaging storm surges.

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Storm Surges

Multiple Choice

Which of the following is an impact of weather hazards?

• disruption of transportation services

• increased agricultural productivity

• improved air quality

• reduction in power consumption

Risk Measurement

Tornadoes are typically measured using the Enhanced Fujita (EF) Scale. This scale classifies tornadoes based on wind speed and the damage they cause. The EF scale covers tornadoes ranging from 65 to over 200 miles per hour.

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Enhanced Fujita Scale

This scale classifies tornadoes based on wind speed. Hurricanes are ranked from Category 1 to Category 5, with Category 5 storms having the strongest winds. The Saffir-Simpson Hurricane Wind Scale also factors in wind and storm surge damage.

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affir-Simpson Hurricane Wind Scale

Multiple Choice

Meteorologists observe several trees uprooted following a tornado that passed through a town. They also observe that some houses are missing roofs, but most structures are still standing. How would the meteorologists classify this tornado on the Enhanced Fujita Scale?

• EF4

• EF2

• EF5

• EF3