Severe Weather and Floods

Severe Weather and Floods

Middle School

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Learning Objectives

• Define and differentiate between winter storms, thunderstorms, hurricanes, and tornadoes.

• Explain how data helps forecast future catastrophic events.

• Describe the formation and characteristics of hurricanes and tornadoes.

• Understand the difference between a weather 'watch' and a 'warning.'

Key Vocabulary

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Storm

A storm is a violent disturbance in the atmosphere, often bringing strong winds, rain, snow, or hail.

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Thunderstorm

A thunderstorm is a specific type of storm that is characterized by the presence of lightning and thunder.

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Hurricane

A hurricane is a very large, powerful rotating storm that forms over warm ocean waters near the equator.

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Tornado

A tornado is a violently rotating column of air that extends from a thunderstorm to the ground.

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Storm Surge

A storm surge is an abnormal rise of water generated by a storm, over and above the predicted astronomical tides.

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Flood

A flood is an overflow of a large amount of water beyond its normal limits, especially over normally dry land.

Key Vocabulary

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Drought

A drought is a long period of time with unusually low rainfall, leading to a shortage of water.

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Forecast

A forecast is a prediction or estimate of future events, such as what the weather will be like.

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Mitigation

Mitigation means taking action to reduce the severity, seriousness, or painfulness of the impact of something bad.

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Natural Hazard

A natural hazard is a threatening event that occurs in the natural world and can cause harm to people.

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Magnitude

Magnitude describes the great size, scale, or importance of an event, such as an earthquake or storm.

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Frequency

Frequency refers to how often an event occurs over a specific period, like how many times it floods.

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What Is a Severe Storm?

• A storm is a violent disturbance in the atmosphere with rapid air movements.

• This is caused by sudden changes in the atmosphere's air pressure.

• The main types are winter storms, thunderstorms, hurricanes, and tornadoes.

• Understanding each storm's unique characteristics and risks is crucial for safety.

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Multiple Choice

What is the definition of a storm?

• A violent disturbance in the atmosphere

• Any form of rain or snow

• A sudden increase in temperature

• A day with a lot of clouds

Multiple Choice

What causes the rapid air movements that characterize a storm?

• The rotation of the Earth on its axis

• The changing of the seasons from summer to winter

• Sudden changes in the atmosphere's air pressure

• The gravitational pull of the moon

Multiple Choice

Considering that storms like thunderstorms and hurricanes have different characteristics, why is it crucial to identify which type of storm is approaching?

• To decide what clothing to wear for the day

• To prepare for the specific dangers each storm presents

• To predict the exact time the storm will arrive

• To know how long the storm will last

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Winter Storms and Thunderstorms

Winter Storms

• ​These storms occur when air is colder than 0°C, causing precipitation to fall to the ground as snow.

• ​​Lake-effect snow happens when cold air moves over a warmer Great Lake, picking up moisture and heat.

• ​This rising air cools and then releases large amounts of snow on the land on the other side.

Thunderstorms

• ​These storms form when warm, humid air is forced upward, creating very tall thunderhead clouds.

• ​​Lightning is a powerful discharge of electrical charges that builds up inside the storm clouds.

• ​Thunder is the explosive sound created when lightning rapidly heats the air, causing a shockwave.

Multiple Choice

What key condition is required for a winter storm to produce snow instead of rain?

• The air temperature is colder than 0°C.

• Warm, humid air is forced upward.

• Cold air moves over a warmer lake.

• Electrical charges build up in clouds.

Multiple Choice

What is the relationship between lightning and thunder during a thunderstorm?

• Two clouds collide with each other.

• Warm, humid air is forced upward.

• Lightning heats the air, causing a shockwave of sound.

• Snow falls from very tall thunderhead clouds.

Multiple Choice

If a mass of cold air moves over the surface of a large, warm lake, what is the most likely weather outcome for the land on the other side?

• The formation of a thunderstorm over the lake.

• Heavy lake-effect snow on the land across the lake.

• The sky will clear as the cold air sinks.

• A powerful discharge of lightning over the water.

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Hurricanes: Formation and Structure

• Hurricanes are powerful storms that form over warm, humid ocean air.

• ​Rising air creates low pressure, forming spiraling winds and rain.

• The center has a calm eye surrounded by the powerful eyewall.

• A dangerous storm surge can cause massive flooding during landfall.

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Multiple Choice

What condition is necessary for a hurricane to begin to form?

• They form over cold, dry land.

• They form over warm, humid ocean air.

• They form in high-pressure systems.

• They form near mountains and valleys.

Multiple Choice

Which statement best describes the relationship between the parts of a hurricane's structure?

• A calm center is surrounded by an area of powerful winds.

• A powerful center is surrounded by an area of calm winds.

• The entire storm has equally powerful winds.

• The storm surge is located in the center of the storm.

Multiple Choice

When a hurricane makes landfall, which combination of factors is responsible for causing the most widespread destruction?

• The calm, clear conditions of the eye.

• The low-pressure area that causes the storm to spiral.

• The powerful winds of the eyewall combined with the flooding from the storm surge.

• The warm ocean water that originally powered the storm.

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Tornadoes: Formation and Damage

• A tornado is a fast-spinning air column from a thunderstorm to the ground.

• It forms when cold air pushes warm air up, creating a rotating funnel.

• Tornado winds are destructive and can reach speeds of up to 500 km/h.

• The Fujita Scale (F0-F5) ranks tornadoes based on the damage they cause.

Multiple Choice

What is a tornado?

• A fast-spinning air column from a thunderstorm to the ground.

• A large, slow-moving storm that forms over the ocean.

• A winter storm that brings heavy snow and ice.

• A type of cloud that produces only gentle rain.

Multiple Choice

What is the relationship between air temperatures that causes a tornado to form?

• When two warm air masses mix together over flat land.

• When cold air pushes warm air upward, causing rotation.

• When the sun heats the ground, causing the air to still.

• When heavy rainfall cools the air near the ground.

Multiple Choice

If a tornado with wind speeds of 500 km/h strikes an area, what conclusion can be drawn?

• It would be ranked as a powerful and destructive tornado on the Fujita Scale.

• It would be considered a weak tornado with a low Fujita Scale ranking.

• It formed from two columns of cold air mixing together.

• It likely caused very little damage to buildings or trees.

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Forecasting Future Events

Analyzing Patterns

• Scientists analyze data from past natural hazards to find important patterns.

• This includes the location, strength, and how often the events occurred.

• Mapping where tornadoes have happened helps identify high-risk areas for the future.

Watching for Signs

• Some severe weather events provide warning signs, called precursor phenomena, before they happen.

• For hurricanes, a key sign is a low-pressure system over warm water.

• Large thunderhead clouds can be a sign that a thunderstorm is developing.

Multiple Choice

What is the main reason scientists analyze data from past natural hazards?

• To find patterns that help forecast future events.

• To change the weather in high-risk areas.

• To count how many scientists study weather.

• To stop natural hazards from happening completely.

Multiple Choice

What is the relationship between a low-pressure system over warm water and a hurricane?

• The low-pressure system is a result of a hurricane.

• The low-pressure system is a warning sign that a hurricane may be forming.

• Hurricanes cause low-pressure systems to disappear.

• Low-pressure systems only happen after a hurricane is over.

Multiple Choice

A scientist is in an area that historical maps identify as high-risk for tornadoes. If the scientist then observes large thunderhead clouds forming, what is the most logical conclusion?

• A hurricane is about to form over the land.

• A severe thunderstorm may be developing, increasing the immediate risk.

• The area is no longer at high risk for tornadoes.

• The historical maps of the area must be incorrect.

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Technology for Mitigation

Global Technologies

• Mitigation means taking action to reduce the impact of natural hazards on people and property.

• Global technologies are systems that have the ability to monitor large-scale events around the world.

• For instance, satellite systems are used to track the development and path of hurricanes.

Local Technologies

• Local technologies are designed and constructed to protect specific communities from natural disasters.

• One example is building basements or storm shelters in areas that experience tornadoes.

• Building levees along rivers prevents flooding, while reservoirs can store water to reduce droughts.

Multiple Choice

What is the primary goal of mitigation?

• To reduce the impact of natural hazards on people and property.

• To predict the exact time a natural disaster will occur.

• To change the weather patterns of a specific region.

• To study the history of past natural disasters.

Multiple Choice

What is the key difference between global and local technologies for mitigation?

• Global technologies are for hurricanes, while local technologies are for tornadoes.

• Global technologies are more expensive than local technologies.

• Global technologies monitor worldwide events, while local technologies protect specific communities.

• Global technologies use satellites, while local technologies use reservoirs.

Multiple Choice

A town situated in a low-lying area next to a large river is seeking to prevent its homes from being destroyed by rising water levels. Which action represents the most direct and effective mitigation strategy for this specific problem?

• Using satellite systems to track the river's path.

• Building levees to contain the river's water.

• Constructing storm shelters for residents to use.

• Creating reservoirs to store water for droughts.

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Floods and Droughts

Floods

• ​A flood is an overflow of water that covers land that is normally dry.

• ​​They are often caused by heavy rain from storms or quickly melting snow and ice.

• ​Dams and levees are built to control water flow and prevent a river from overflowing.

Droughts

• ​A drought is a long period with very little or no rainfall in an area.

• ​​These are usually caused by hot, dry weather systems that do not move for weeks.

• ​They can cause crop failures, and reservoirs are built to store water for dry times.

Multiple Choice

What is the definition of a flood?

• An overflow of water that covers land that is normally dry.

• A long period with very little or no rainfall in an area.

• A structure built to control the flow of water in a river.

• A storage area for water to be used during dry times.

Multiple Choice

How do the causes of floods and droughts differ?

• Floods are caused by heavy rain or melting snow, while droughts are caused by long periods of no rain.

• Floods are caused by hot, dry weather, while droughts are caused by storms or melting ice.

• Floods are caused by building reservoirs, while droughts are caused by building levees.

• Floods are caused by crop failures, while droughts are caused by overflowing rivers.

Multiple Choice

A town is located near a river that often floods after heavy rain, but the area also suffers from very dry summers. Which strategy would best address both of these problems?

• Building levees to contain the river and a reservoir to store water for dry periods.

• Building a reservoir to prevent the river from overflowing during storms.

• Building dams and levees to provide water for crop irrigation during dry periods.

• Building one large dam to both prevent flooding and store water for droughts.

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Storm Safety Procedures

Storm Watch

• A storm watch means that conditions are right for severe weather to form in your area.

• This is a heads-up to be prepared and stay aware of changing weather conditions.

• You should keep an eye on the news and have a safety plan ready to go.

Storm Warning

• A storm warning means severe weather has been spotted and is heading your way soon.

• This is a more serious alert, meaning you are in immediate danger and must act now.

• You should take shelter immediately in a safe place, like a basement or an interior room.

Multiple Choice

What is the key difference between a storm watch and a storm warning?

• A watch means a storm might form, while a warning means a storm is already happening.

• A watch is for winter storms, while a warning is for summer storms.

• A watch requires you to take shelter, while a warning requires you to watch the news.

• A watch is a less serious alert than a warning, but both mean a storm is happening.

Multiple Choice

Why do the recommended safety actions differ between a storm watch and a storm warning?

• A warning means the storm is an immediate danger, while a watch means you should prepare for potential danger.

• A watch is always issued after a warning has ended.

• A warning is for a small area, while a watch is for a very large area.

• A warning means you have several days to prepare, while a watch means you have only a few minutes.

Multiple Choice

Your local news reports that conditions in your area are favorable for a severe storm to develop this afternoon. What is the most appropriate action to take?

• Take shelter in the basement immediately.

• Keep listening to the news and make sure your safety plan is ready.

• Ignore the alert until it is upgraded to a warning.

• Evacuate the area as quickly as possible.

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Common Misconceptions

Misconception	Correction
Weather prediction is just guessing.	Forecasting uses data to find patterns and make reliable predictions.
Hurricanes and tornadoes are the same thing.	Hurricanes are large storms over oceans; tornadoes form over land.
The biggest danger from a hurricane is the wind.	The storm surge and flooding cause the most destruction.

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Summary

• Severe weather includes winter storms, thunderstorms, hurricanes, and tornadoes.

• Scientists analyze data to forecast events, and technology helps reduce their impact.

• Hurricanes are large ocean storms, while tornadoes are rotating funnels of air over land.

• A storm watch means be prepared; a warning means to take immediate action.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

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