Severe Weather

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Storm Noun

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[storm]

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Storm

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A violent atmospheric disturbance with rapid air movements, strong winds, and precipitation like rain, snow, or hail.

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Example: This diagram uses a speedometer to show how storms are classified by their maximum sustained wind speeds, from Tropical Depression to Tropical Storm to Hurricane.

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Troposphere Noun

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[troh-puh-sfeer]

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Troposphere

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The lowest layer of Earth's atmosphere, where nearly all weather phenomena, including storms, occur and are contained.

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Example: This diagram shows the layers of the atmosphere, identifying the Troposphere as the lowest layer extending from the Earth's surface up to about 10 km.

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Unstable Air Noun

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[uhn-stey-buhl air]

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Unstable Air

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An atmospheric condition where surrounding air is colder than lower-level air, promoting a storm's vertical growth and intensity.

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Example: Solar radiation heats the Earth's surface, causing the air above it to warm up, become less dense, and rise, which demonstrates atmospheric instability.

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Updraft Noun

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[uhp-draft]

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Updraft

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An upward current of air within a storm, typically caused by the rapid rising of warm, humid air.

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Example: The sun heats the ground, causing the air above it to warm up, become less dense, and rise, creating an upward current of air called an updraft.

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Downdraft Noun

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[doun-draft]

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Downdraft

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A downward current of cool, dry air within a storm cloud that pulls heavy precipitation toward the ground.

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Example: This diagram shows a thunderstorm where cool, dense air sinks toward the ground, creating a 'cool downdraft' that often brings precipitation with it.

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Thunderstorm Noun

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[thuhn-der-storm]

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Thunderstorm

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A storm producing thunder and lightning, formed when warm, humid air is forced upward, creating tall cumulonimbus clouds.

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Example: A thunderstorm forms when three ingredients are present: moisture (from water vapor), warm unstable air (that rises), and a lifting mechanism (like a weather front).

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Lightning Noun

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[lahyt-ning]

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Lightning

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A powerful discharge of electrical charges that builds up inside storm clouds and is released as visible electricity.

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Example: This diagram shows how lightning forms when positive charges collect at the top of a thundercloud and negative charges at the bottom, creating an electrical discharge.

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Thunder Noun

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[thuhn-der]

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Thunder

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The explosive sound created when a lightning strike rapidly heats the surrounding air, causing a powerful shockwave.

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Example: This diagram shows how air currents inside a storm cloud separate positive and negative electrical charges, creating the conditions for lightning and thunder.

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Tornado Noun

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[tor-ney-doh]

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Tornado

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A violently rotating, funnel-shaped column of air that extends from the base of a thunderstorm to the ground.

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Example: This diagram shows that a tornado's destructive power is greatest at its core, with wind speed and damage decreasing as distance from the center increases.

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Waterspout Noun

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[waw-ter-spout]

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Waterspout

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A rotating column of air and water mist, essentially a tornado that forms over a body of water.

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Example: This diagram shows how a waterspout forms when cool air moves over warm water, causing the warm, moist air to rise and create a rotating column.