Storms Overview
Introduction to Storms
A storm is a violent disturbance in the atmosphere characterized by significant weather changes.
Key characteristics include sudden changes in air pressure, temperature, and humidity that cause movements in air masses, which can lead to various weather phenomena.
Four main types of storms: Thunderstorms, Tornadoes, Hurricanes, and Winter Storms.
Thunderstorms
Definition: A thunderstorm is a small but intense storm often accompanied by heavy precipitation, thunder, and lightning.
Formation of Thunderstorms:
Cumulonimbus Clouds: Thunderstorms form in large cumulonimbus clouds, sometimes called thunderheads, which are towering clouds with a characteristic anvil shape at their tops.
Ideal Conditions: Most common in hot, humid afternoons when warm, moist air is forced upward along a cold front, creating instability in the atmosphere.
Cooling and Condensation: As the air rises and cools, it can condense to form dense thunderheads, leading to heavy rain, hail, and potentially severe weather events.
Air Movements: Thunderstorms are characterized by strong updrafts (rising air) and downdrafts (falling air), with updrafts feeding the thunderstorm and downdrafts signalling the storm's decay.
Lightning and Thunder:
Lightning: Defined as a sudden spark or electrical discharge occurring within clouds or between a cloud and the ground, lightning can reach temperatures of around 54,000°F, which is hotter than the surface of the sun.
Speed of Light vs. Sound: Light travels significantly faster than sound, which is why we typically see lightning before hearing thunder. This phenomenon can help estimate how far away a storm is based on the time difference between lightning and thunder.
Thunder: The sound produced by lightning as it heats the air, causing a rapid expansion leading to the characteristic rumble of thunder that we hear during storms.
Thunderstorm Damage and Safety:
Thunderstorms can cause severe damage, such as uprooting trees, damaging structures, and causing flash floods, which can result in dangerous situations for both people and wildlife.
Flooding: Flash flooding occurs when water overflows the banks of rivers or streams rapidly, particularly in urban settings where water cannot be absorbed by the ground effectively.
Safety Tips:
Stay indoors during thunderstorms, particularly away from windows and doors.
Avoid electrical devices and outlets; do not touch metal objects in vehicles, as they can conduct electricity.
If outdoors, seek shelter in a sturdy building or vehicle, away from trees and water bodies.
Severe Thunderstorm Safety:
Understanding severe thunderstorm warnings is crucial for safety:
Watch: Conditions are favorable for the development of thunderstorms, indicating that one may form soon.
Warning: A thunderstorm is currently occurring; take immediate shelter as the conditions may lead to severe weather.
Severe thunderstorms may produce hazardous elements such as:
Large hail that can damage crops and vehicles.
Strong wind gusts that can lead to wind damage.
Flash floods, posing risks to life.
Tornadoes, which can form under certain conditions within severe thunderstorms.
Tornadoes
A tornado is a rapidly rotating funnel-shaped cloud that reaches down from a storm cloud to touch the Earth's surface, often exhibiting extreme violence.
Water Spout: Tornadoes that occur over large bodies of water are called waterspouts, which can also be highly destructive.
Wind Speeds: Tornado wind speeds can exceed 300 mph, with some estimates reaching up to 500 km/h (about 310 mph), making them one of the most powerful weather phenomena.
Tornadoes form in regions that favor cold air colliding with warm, humid air, typical of the Great Plains in the United States.
A common mechanism for tornado formation includes:
A maritime tropical air mass moving north from the Gulf of Mexico interacting with a continental polar air mass from Canada, forcing warm air upward and creating severe thunderstorms, which can lead to tornadoes.
Tornado Alley: This term refers to the region in the U.S. where tornadoes are most frequently encountered, averaging about 800 tornadoes annually, primarily in states like Texas, Oklahoma, and Kansas.
Tornado Damage and Safety:
Tornado Damage: Tornadoes can lead to catastrophic consequences, with strong winds and flying debris posing major risks; they can destroy structures, uproot trees, and result in fatalities.
Fujita Scale: This scale categorizes tornadoes from F1 (light damage) to F5 (extreme damage), allowing meteorologists and emergency responders to assess and communicate the severe effects of a tornado.
Safety Measures:
Tornado Watch: Issued when conditions are conducive to tornado formation, indicating increased risk.
Tornado Warning: Issued when a tornado has been sighted or indicated by radar, advising immediate action to take shelter.
Seek shelter in a sturdy storm shelter, basement, or interior room on the ground floor, away from windows and doors. If outdoors, lie flat in a ditch for maximum protection.
Hurricanes
Definition: A hurricane is a tropical cyclone with sustained winds exceeding 119 km/h (74 mph), categorized based on wind speed and potential damage.
Regional Names: In the Atlantic, Pacific, and Indian Oceans, hurricanes are also referred to as typhoons or cyclones, depending on their geographic location.
Formation Process:
Warm, moist air rushes to the hurricane's low-pressure center, where it rises and cools, forming cumulonimbus clouds that facilitate thunderstorms and further strengthen the system.
The rising warm air collects heat and moisture from the ocean, fueling cyclonic winds.
In mature hurricanes, a calm area called the eye forms in the center, surrounded by the eye wall where the strongest winds occur.
As the storm moves, the air expelled outward at high altitudes creates outflow that helps move the storm forward.
Hurricane Damage and Safety:
Hurricanes can lead to substantial damage from high winds and storm surges, which cause extensive flooding.
Storm Surge: This term refers to a dome of water created by the wind and pressure differences that sweep across the coast where the hurricane makes landfall, often leading to devastating coastal flooding.
Hurricane Watch: Indicates potential hurricane conditions within 36 hours.
Hurricane Warning: Signals that hurricane conditions are imminent within 24 hours; evacuation may be necessary to ensure safety.
Winter Storms
Winter storms bring heavy snowfall that can obstruct roads, trap people indoors, and hinder emergency services from reaching critical areas in need.
Extreme cold temperatures can cause damage to crops and lead to water pipes freezing and bursting, with significant economic impacts.
Lake Effect Snow: A significant weather phenomenon around the Great Lakes wherein cold, dry air from Canada moves across the warmer lake waters, picking up moisture and heat. This moist air, upon reaching the land, cools and condenses, leading to heavy snowfall that can exceed 10 feet per year in certain areas.
Snow Storm Safety
Blowing snow significantly limits visibility, making it easy for individuals to become lost and increasing the risk of hypothermia due to exposure to harsh winds and cold.
Safety Recommendations:
Seek shelter from the wind and find a warm location to avoid exposure.
Cover all exposed skin to prevent frostbite and remain dry, as wet clothing can increase heat loss.
If trapped in a vehicle, only run the engine if the exhaust pipe is clear of snow to prevent carbon monoxide poisoning, ensure to keep the heater running intermittently to maintain warmth.