Tornadoes and Heat

What is a tornado?

Rapidly rotating column of air spiralling around a center of low atmospheric pressure

What are the properties of tornadoes?

Form from large thunderstorms, accompanied by heavy rain or hail, highest wind speed of any weather phenomena, form in high atmosphere

What is the regional scale of tornado formation?

Warm humid air from Gulf of Mexico, cold, dry mid-altitude Canadian/Rocky Mountain air and fats high altitude jet stream air meet and make thunderstorm, different directions produce corkscrew effect

How do supercell thunderstorms form tornadoes?

Tilt or supercell moves warm updraft providing rotation that spins off, wall clouds form where powerful tornadoes emerge, rotation develops in wide zone which core pulls into tighter spiral as speed increases

What is a hook echo?

High reflectivity area in radar image shaped like a hook which indicates potential tornado

What is a mesocyclone?

Vortex of air, approximately 2-10 miles in diameter, within a convective storm

What is the vortex scale method or tornado formation?

Air mass collisions in lower atmosphere create horizontal tube of air spinning parallel to ground, warm rising air provides vertical wind shear that lifts the spinning tube of air, as it rises, diameter decrease and velocity increases as it stretches

When do tornadoes occur?

Late spring, early summer

How do tornadoes kill?

Wind blowing buildings/trees, wind blown debris impacts, wind removes roofs and empty contents of house

What factors make tornado deaths more likely?

Elderly, mobile homes, exterior rooms with windows, lack of warning

What is the Fujita Scale/F Scale?

Uses damage to structures and trees to estimate wind speed or tornadoes just above ground, F0-F5

What is the Enhanced Fujita scale?

More precise Fujita scale, EF0-EF5

How does a tornado destroy a house?

Flying debris shatters windows, wind under eaves and through windows raises pressure, lifting the roof, once roof is gone the walls are less supported, exterior walls go, then front and back, inside walls progressively felled

What are safe rooms during tornadoes?

Cellars, interior closet like rooms with thick concrete walls and roof

How to prepare for a tornado?

Stay informed, pay attention to weather warnings, move family to lowest level of building, stay away from windows/outside walls/doors, get under heavy piece of furniture, do not stay in buildings with large expanse of glass, get out of vehicles and mobile homes

How to prepare for tornadoes outside?

Do not try to outrun with vehicle, lie down in ditch away from power lines and cover head, do not go under overpass/bridge

What is a heat wave?

Extended period or extreme heat (in Canada, 2 days with humidex above 42 degrees C)

What is humidex?

Humidity index, how hot weather feels to the average person

What causes a heat wave?

Long lasting high pressure ridge in upper troposphere

What is an anticyclone?

Clockwise rotations where warm air descends, warming further and lowering humidity which sucking up moisture over land

What is hyperthermia?

Body temperature above 40 degrees C

What are signs of heat exhaustion/stroke?

High body temperature, confusion, staggering, strange behaviour, fainting, dry skin with rapid or slow pulse

What are properties of a cyclone?

Thunderstorms and lightning, low pressure, rising warm moist air, cloudy weather

What are the properties of an anticyclone?

Heat wave, high pressure, descending cool, dry air, clear weather

What are urban heat islands?

Cities are warmer than surrounding hinterlands, up to 10 degree difference at night

Why do urban heat islands occur?

Concrete, asphalt, and stone absorb heat during the day and release it at night, less evapotranspiration than undeveloped areas

Who is most affected by heat waves?

Those without air conditioning, elderly, living on top floors of buildings

What can increase heatwaves?

Dried out vegetation, air pollution, rising temperature, rising population, urbanization

How to prepare for a heat wave?

Stay hydrated and cool, check with neighbours, friends and at risk individuals, be prepared for power outages, have emergency plan, emergency kit, use air conditioning, slow down activities, stay informed, pay attention to weather warnings

What are signs of heat stroke?

Signs of heat exhaustion, unconsciousness, confusion, stopped sweating