Understanding Tropical Storms and Natural Hazards

• A hazard is a threat, either natural or human, with the potential to cause loss of life, injury, property damage, socio-economic disruption, or environmental degradation.
• Natural hazards are naturally occurring events posing a threat to human populations and infrastructure.

Tropical Storms

• Tropical storms are rotating, organized systems of clouds and thunderstorms originating over warm tropical waters.
• Characterized by closed low-level circulation and maximum sustained winds between 39-73 mph.
• When winds reach 74 mph or higher, the storm is classified as a hurricane (Atlantic and eastern Pacific) or typhoon (western Pacific).
• Key formation conditions: warm ocean waters (at least 26.5°C), atmospheric instability, high humidity in the lower to middle troposphere, and low vertical wind shear.
• Wind shear, the change in wind speed or direction with height, can disrupt storm development.
• They typically form between 5 and 20 degrees latitude from the equator.
• The Coriolis effect (due to earth's rotation) is necessary for the storm to spin.
• The eye, the relatively calm center of the storm, features descending air.
• The eyewall is the most intense part of the storm, with the strongest winds and heaviest rainfall.
• Rainbands are outer bands of thunderstorms that spiral inward toward the storm's center.
• Tropical storms are measured using the Saffir-Simpson Hurricane Wind Scale.
• The scale classifies hurricanes based on maximum sustained winds, ranging from Category 1 (74-95 mph) to Category 5 (157 mph or higher).
• Storm surge is an abnormal rise of water generated by a storm, exceeding predicted astronomical tides.
• High winds can cause structural damage, uproot trees, and create flying debris.
• Flooding can result from heavy rainfall (inland) and storm surge (coastal).
• Landslides can be triggered by intense rainfall saturating the ground, especially in mountainous areas.

Hurricane Sandy Case Study

• Hurricane Sandy formed in the Caribbean Sea in late October 2012, moving northward and making landfall in New Jersey as a strong post-tropical cyclone on October 29, 2012.
• Sandy was a hybrid storm, transitioning from a hurricane to a post-tropical cyclone near the Mid-Atlantic coast but maintaining hurricane-force winds.
• A strong high-pressure system over Greenland blocked Sandy, causing an unusual westward turn into New Jersey.
• The storm surge reached record levels in New York City, causing widespread flooding.
• High winds caused widespread power outages, and heavy rainfall led to inland flooding.
• Impacts included at least 233 deaths across affected regions (Caribbean, U.S., and Canada).
• Economic losses in the United States were estimated at $75 billion, making it one of the costliest U.S. natural disasters.
• Severe damage occurred to transportation, power, and communication infrastructure, with hundreds of thousands of homes damaged or destroyed.
• Hundreds of thousands of people were displaced from their homes.
• Responses included mandatory and voluntary evacuations in coastal areas.
• Emergency services provided search and rescue operations, shelters, and medical assistance.
• The U.S. federal government provided billions in disaster relief and recovery funds.
• Efforts focused on restoring power, repairing transportation systems, and rebuilding damaged infrastructure.

Wildfires

• Wildfires are uncontrolled fires burning in wildland areas, often consuming forests, grasslands, and shrublands.
• Natural causes: Lightning strikes are a common natural cause of wildfires.
• Human causes: Most wildfires are started by human activities, such as unattended campfires, discarded cigarettes, and arson.
• Key conditions for wildfires include dry vegetation, hot temperatures, and strong winds.
• Dry vegetation provides fuel for the fire to burn.
• Hot temperatures increase evaporation, making vegetation drier and more flammable.
• Strong winds spread the fire quickly and make it more difficult to control.
• Surface fires burn along the ground, consuming leaf litter, grasses, and small shrubs.
• Crown fires burn in the tops of trees and are the most intense and destructive type of wildfire.
• Impacts include fatalities among firefighters and civilians.
• Property damage: Wildfires can destroy homes, businesses, and other structures.
• Environmental damage: Wildfires can destroy forests, pollute air and water, and disrupt ecosystems.
• Economic losses can be significant due to property damage, business interruption, and suppression costs.
• Responses:
  • Prevention measures reduce wildfire risk, such as clearing brush around homes and educating the public about fire safety.
  • Suppression efforts control and extinguish wildfires, using firefighters, aircraft, and other resources.
  • Prescribed burns are controlled burns intentionally set to reduce available fuel.
  • Land management practices promote healthy forests and reduce wildfire risk.

Tornadoes

• Tornadoes are violently rotating columns of air extending from a thunderstorm to the ground.
• Key conditions for formation include:
  • Supercell thunderstorms: Rotating thunderstorms with a well-defined mesocyclone.
  • Warm, moist air at the surface: Provides instability and energy for the storm.
  • Cold, dry air aloft: Creates a steep temperature gradient, enhancing instability.
  • Wind shear: Changes in wind speed and direction with height, which can cause the storm to rotate.
• They are most common in the "Tornado Alley" region of the United States, including states such as Texas, Oklahoma, Kansas, and Nebraska.
• Measured using the Enhanced Fujita (EF) Scale, which classifies tornadoes based on damage caused, ranging from EF0 (weak) to EF5 (violent).
• High winds: Can cause catastrophic damage to buildings, trees, and other structures.
• Flying debris: Tornadoes can pick up and hurl debris over long distances, causing injuries and damage.
• Hail: Large hailstones can cause damage to cars, roofs, and crops.
• Flash flooding: Heavy rainfall from thunderstorms that produce tornadoes can lead to flash flooding.
• Can cause fatalities among people caught in their path.
• Can destroy homes, businesses, and other structures.
• Flying debris and collapsing buildings can cause injuries.
• Can cause significant economic losses due to property damage, business interruption, and emergency response costs.
• Responses:
• Warnings: The National Weather Service issues tornado watches and warnings.
• Sheltering: Seeking shelter in a basement, storm cellar, or interior room away from windows is advised.
• Education: Public education campaigns promote awareness about tornado safety.
• Emergency management: Local and state agencies coordinate responses.

UK Storms

• The UK experiences a variety of storms, including:
• Extratropical cyclones: Large-scale weather systems that form outside the tropics.
• Winter storms: Often associated with strong winds, heavy rainfall, and snow.
• Summer thunderstorms: Can bring heavy rain, hail, and lightning.
• Extreme wind speeds: Can cause structural damage to buildings, uproot trees, and disrupt transportation.
• Heavy rainfall: Can lead to flooding, especially in urban areas.
• Snow and ice: Can disrupt transportation and cause accidents.
• Coastal erosion: Storm surges can cause significant coastal erosion.
• Impacts:
  • Loss of life: Severe storms can cause fatalities, especially due to flooding and high winds.
  • Property damage: Storms can damage homes, businesses, and other structures.
  • Infrastructure disruption: Storms can disrupt transportation, power, and communication infrastructure.
  • Economic losses: Storms can cause significant economic losses due to property damage, business interruption, and emergency response costs.
• Responses:
  • Forecasting: The Met Office provides weather forecasts and warnings.
  • Flood defenses: Flood barriers, embankments, and other structures are used.
  • Emergency services: Fire and rescue services respond to emergencies.
  • Public awareness: Public education campaigns promote awareness.

Formation of Tropical Storms and Hurricanes

• Tropical storms and hurricanes form over warm ocean waters near the equator.
• Warm ocean water provides the necessary heat and moisture to fuel the storm.
• Atmospheric instability allows air to rise and form thunderstorms.
• High humidity provides additional moisture for the storm to grow.
• Low wind shear allows the storm to develop and intensify.
• Coriolis effect causes the storm to rotate.
• Tropical disturbance: A cluster of thunderstorms that can develop into a tropical storm.
• Tropical depression: A tropical disturbance with a closed circulation and maximum sustained winds of 38 mph or less.
• Tropical storm: A tropical depression with maximum sustained winds between 39-73 mph.
• Hurricane: A tropical storm with maximum sustained winds of 74 mph or higher.

Hurricane Sandy Formation Case Study

• Formation: Sandy began as a tropical wave in the Caribbean Sea in mid-October 2012.
• Intensification: The storm intensified into a hurricane as it moved northward, fueled by warm waters and favorable atmospheric conditions.
• Hybridization: As Sandy approached the Mid-Atlantic coast of the United States, it began to transition into a post-tropical cyclone, merging with an extratropical cyclone.
• Landfall: Sandy made landfall in New Jersey as a strong post-tropical cyclone on October 29, 2012.
• Unusual track: Sandy took an unusual westward turn into New Jersey due to a blocking high-pressure system over Greenland.
• Storm surge: Sandy's storm surge was particularly devastating, reaching record levels in New York City and causing widespread flooding.
• Impacts: Sandy caused widespread damage and disruption across the Mid-Atlantic region, including deaths, property damage, and power outages.

Learn about natural hazards focusing on tropical storms, their characteristics, and conditions for formation. Discover the role of warm ocean waters, atmospheric instability, humidity, and wind shear in tropical storm development and classification as hurricanes or typhoons.