Wild, weird, and wonderful weather

This heat becomes part of a great balancing act taking place in the troposphere, where warm and cold air is continually being transported to other areas of the planet as it tries to reach a balance (or equilibrium).

If one part of the troposphere becomes hotter than another, the air molecules in that area will expand, causing the pressure to increase.

This increase in pressure causes air to move from the hotter area to the cooler area.

Given Earth's orientation to the sun, areas near the equator receive more sunlight (and higher temperatures) than other parts of the planet.

This results in warm air moving toward the poles and cold air moving south to the equator.

Weather forms along the boundaries that exist between cold and warm fronts of air mass.

A good example is Tornado Alley, located in the central Plains of the United States and a small part of the Canadian Prairies. Here, we can see everything from ice storms, blizzards, flooding rains, and, in the spring season, tornadoes.

The reason why this area is so active is because it is at the boundary of multiple air fronts.

They include the collision of warm and moist air from the Gulf Of Mexico and cold, dry air from Canada (after the winter season).

All these ingredients can come together to create a low-pressure system, where strong storms can arise.

On a hot summer day in the Canadian Prairies, the sun will heat the ground and air will rise from the surface into colder air above.

This upward force of air is called the updraft.

When an unstable and buoyant air mass bubbles up all day, this is known as convection. The convection process is created by the heating of the surface of the Earth, which causes warm air to rise.

On a convective day, we can see some of the strongest thunderstorms on Earth in the central plains of the United States and the Canadian Prairies.

Tall cumulonimbus clouds expanding out of the troposphere and into the stratosphere can reach a height of about 12,000 metres, sometimes going as high as 19,000 metres.

Did you know? Moisture-laden thunderstorms provide a significant percentage of the annual rainfall needed by farmers in the corn belt of the United States, the Plains, and the Canadian Prairies.

Strong updrafts can also suspend water at low temperatures long enough to produce ice balls that we know as hail.

These hailstones can be as small as peas or as large as softballs, and they can cause injuries, as well as extensive damage to property and farmers' fields.

Did you know? The largest hailstone in Canada was 293 grams in weight and 12.3 centimetres in diameter, recovered near Innisfail, Alta., in 2022.

The largest hailstone ever found, shown below, was recovered in Vivian, South Dakota, and has the world record for both diameter (20 cm) and weight (879 g).

When there is a thunderstorm, there are a lot of tiny particles inside the clouds with electric "charges". Some are positive and some are negative. They move around and bump into each other, which creates a lot of energy.

Eventually, this energy builds up to the point that it has to be released somehow. That's when lightning happens! Lightning can move from a cloud to the ground or from one cloud to another.

Lightning is easy to imagine as the static electricity that builds up when you rub your feet across the carpet and touch a doorknob. Zap!

Did you know? Researchers have found that the energy in one single thunderstorm could power an entire city for several minutes!

By  definition , a tornado is a violently rotating column of air touching the ground, usually attached to the base of a thunderstorm.

This rotating column of air, however, is a small part of the overall large thunderstorm.

Imagine a high heel shoe on a woman's foot. If the heel on her shoe was the tornado, then to put it into perspective, her body is the cumulonimbus cloud that stretches well into the upper atmosphere.

A tornado is a rare weather event to witness in person and thousands of people travel to the Canadian Prairies and the U.S. Plains hoping to catch a glimpse of one. These include scientists, broadcast journalists, adrenaline seekers, and many others.

Did you know? The United States sees approximately 1,200 tornadoes per year and many occur in May and June, while Canada averages 80-100 tornadoes per year and they mostly occur in June and July.

The distinct difference between a regular thunderstorm and one that produces a tornado is something called a mesocyclone.

A mesocyclone is what forms when a thunderstorm is rotating or when the updraft starts to spin. 

Tornadoes can come in all shapes and sizes.

The rope tornado is long and skinny and is usually seen at the beginning or end of the tornado life cycle.

There is the cone tornado, which looks like an ice cream cone.

The wedge tornado, which is as wide as it is tall, is rare and can cause widespread damage.

Stovepipe tornadoes, which are of a consistent width from top to bottom, are also possible, as well as many others.

Did you know? The world’s largest tornado happened in El Reno, Oklahoma, on May 31, 2013. It was 4.2 kilometres wide and difficult for storm chasers to see as it was “rain-wrapped” (i.e., surrounded by moisture from the parent thunderstorm).

The rating scale that is used for tornadoes is called the Enhanced Fujita Scale and is based on wind speeds and damage done to an area.

Based on mobile RADAR data, the world’s largest tornado had winds that were as fast as 476 km/hr. However, it was only rated an EF3 because it didn’t cause much damage.

Another driving factor of our complex weather patterns is ocean temperatures. If you have ever heard of La Niña and El Niño, you might know that temperatures in the eastern Pacific Ocean can affect weather around the world.

If the water temperatures are warmer than normal off the coast of South America, then it will be deemed an El Niño season. If it is a La Niña, then that means temperatures are colder than normal off the coast of South America.

Water has a higher specific heat capacity than air, which means that it takes longer to heat and cool.

This is why cities like Vancouver, B.C., and San Diego, Calif., have mild temperatures and consistent weather all year.

The ocean acts like a warm, cozy blanket in the winter season but can act like an air conditioning unit in the summer.

If you live near the Great Lakes, you know that on a warm day in the spring season, it will always be a few degrees cooler along the lakeside.

Just like the ocean, lakes can also modify air masses. Winds blowing from the lake to the land, called a lake breeze, can have a cooling effect on nearby communities.

When an Arctic air mass moves in from the poles over the Great Lakes, the lake effect adds warmth and moisture to the air mass, producing snow.

Rising air over the relatively warmer lake waters in the fall and winter seasons can produce several centimetres of snow in cities like London, Ont., and Buffalo, N.Y.

With the right conditions, the lake effect can also produce snow squalls and even freezing spray.

A snow squall is a brief and powerful episode of heavy snowfall that results in a sudden decrease in visibility and is frequently accompanied by strong gusts of wind.

Freezing spray can occur when water from the lake is sprayed or splashed onto surfaces that are cold enough for it to freeze on impact.

There is research being done on whether lake effect snow events could be increasing due to climate change.

In normal conditions, when the lakes freeze up in the wintertime, the lake effect stops. If the lakes are frozen, there is no instability between the warm body of water and the cold air above it.

But what if our lakes never freeze in a season? That could mean that the likelihood for more extreme snow events increases.

Speaking of lakes, let’s turn our attention back to the other powerful water weather driver — the ocean.

Warm water temperatures in the ocean can lead to the “beast” of all weather phenomena…a hurricane!

A hurricane is a large collection of swirling thunderstorms over the warm ocean waters that can reach nearly 500 kilometres in diameter.

Hurricanes are born in Africa. Well, sort of. The dry and dusty Sahara Desert experiences convective thunderstorms which can travel over the far eastern parts of the Atlantic Ocean and get picked up by a band of winds known as the easterlies.

These disturbances can consolidate into a hurricane as they travel the width of the Atlantic Ocean, riding the easterlies toward the Caribbean. They can often make landfall, causing extreme wind damage and flooding for U.S. and Canadian residents.

Hurricane strength is measured using the Saffir-Simpson scale, which is based on wind speeds.

One of the most devastating hurricanes in U.S. history was Hurricane Katrina.

It was rated a Category 3 hurricane on the Saffir-Simpson scale when it made landfall along the Gulf Coast of the United States.

It took the lives of 1,833 people and caused damages estimated to be more than $160 billion in the city of New Orleans and its surrounding areas.

Hurricane Katrina boasted winds of 202 km/hr when making landfall in Louisiana.