Toronto is the most populous city in Canada and the provincial capital of Ontario. It is also the international business center, culture, arts, finance, and the most multicultural city globally. The city records some of the most extreme weather conditions compared to any other parts of the country. It has been struggling with the most potent windstorms and gusts since its creation. But why is the city so windy? This post discusses some of the causes of stormy weather in Toronto and its effects.
Before understanding the causes of Toronto’s windy weather, it’s essential to understand a few things about wind. Read on to learn more:
What is Wind?
According to National Geographic, the wind is the movement of air resulting from irregular heating of the earth’s surface by the sun. While you can’t see wind, you can feel its sheer force. This force can be quite powerful such that it can rip enormous trees off the earth or carry ships across oceans.
The atmospheric pressure differences generate the wind.
As the air warms up around the equator, it rises and moves towards the poles creating a low-pressure system. Likewise, cold and dense air moves across the earth towards the equatorial regions, replacing the warm air, and this creates a high-pressure system. Consequently, this difference in pressure will cause air to flow from high- to low-pressure regions, giving rise to winds. The higher the pressure difference, the stronger the winds.
In areas located in the Northern Hemisphere, including Canada, winds get deflected to the right side of motion through the Coriolis effect. This effect typically results from the rotation of the earth and gives rise to prevailing westerly winds.
Factors Affecting Wind Patterns in Toronto
Winds usually blow parallel to isobars (lines of equal pressure) in the atmosphere, 1.2-1.6 kilometers above the surface of the earth. Generally, these winds are referred to as geostrophic winds and are well balanced due to the horizontal Coriolis effect and pressure forces. Like the geostrophic winds, Gradient winds may have the same direction, but they have a faster cyclonic movement, spanning in counterclockwise paths. They may also move slowly in anticyclonic, curved paths, spanning in a clockwise direction. Closer to the surface, the friction causes reduced wind speeds, which is then deflected to low-pressure areas. This process causes lift and wind convergence in lows, resulting in bad weather. However, high-pressure systems, winds diverge, and this leads to good weather in the city.
1. Toronto’s Temperature
Toronto experiences varying temperatures every season, day and night because of atmospheric heat changes of the earth. During the day, the sun heats the air and causes more windy conditions. Different air masses may also differ in temperature. Warm fronts in Toronto are preceded by warm air masses, which are less dense than colder air masses. Hence, the warm air will consequently ride up over the cold air mass, leading to winds. Toronto’s Converselt is a cold front, which is also the leading edge of cold air mass is one of the leading causes of windy conditions in the city.
2. Air Pressure
Typically, air pressure can be defined as a column of air pressing against the atmosphere from the earth’s surface. Ideally, air pressure reduces as altitude increases and will fluctuate on the ground with differences in surface elevations. Furthermore, the wind will always flow horizontally on the earth’s surface from high-pressure regions to low-pressure regions. However, its speed is gauged by the rate of the pressure gradient between two pressure regions. Therefore, the higher the pressure difference, the quicker the wind.
3. Topography of Toronto
Another common cause of windy conditions in Toronto is its proximity to nearby mountains. These mountains include Mount Pisgah (308km), Bald Eagle (336km), and mount Nittany (351km). Winds usually blow rapidly through these mountains, and depending on their shapes, the winds can remain turbulent for some distance from these mountains. After the wind flows over the hills, it’s heated, expands, and forms clouds or rain.
The air then descends on the lee side and becomes highly compressed and dry. Since Toronto is on the lee side of these mountains, the air slides down in a gusty, dry, and strong wind. This type of wind is commonly referred to as Fohn or Chinook. Besides, these types of winds are infamous for their ability to melt snow because they are dry and warm.
4. Centripetal Acceleration
The speed of air will increase with the centripetal forces, and this influences wind direction at the circulation center. Consequently, this acceleration results in a force created at right angles to the wind flow as well as inwards towards the rotation center. Winds in cyclones (low-pressure systems) flow inwards, and anticlockwise in the Northern Hemisphere. However, winds blowing in anticyclone (high-pressure systems) move outwards, and in clockwise in the Northern Hemisphere. Typically, Toronto is in Canada, which is located in the Northern Hemisphere.
5. Earth’s Rotation
The earth’s rotation on its axis results in winds shifting direction and causing prevailing winds. This shift, commonly known as the Coriolis effect, turns winds to the right of the Northern Hemisphere and the left of the Southern Hemisphere. Additionally, middle-latitude westerlies flow from the Northern Hemisphere’s southwest and Southern Hemisphere’s northwest.
6. Toronto’s Tall Skyscrapers and Their Effects to Wind Patterns
They say wind can steal your cap, mess your hair up, or even sweep you off your feet. Well, this is true for most parts of Toronto that experience powerful wind gusts. Some of them can also stretch several city blocks. While mother nature may have a hand in it, the city’s tall towers contribute immensely to the windy conditions. The tall skyscrapers usually shift the course of the wind and redirect it back to the surface where it hits you hard. These areas are often dubbed “wind tunnels,” but weather experts call this “corner vortex,” “channeling,” or “down-washing.”
The tall buildings in Toronto lead to multiple phenomena coinciding. Hence, walking in the city streets can be quite unbearable due to the windy conditions. Since the last century, the city has seen increased development of skyscrapers. However, it’s for the past couple of decades that the city’s management and construction experts started paying attention to how the urban design impacts the environment at surface levels.
According to Richard Anderson, a geography professor at York University, there were many instances of people being swept away and injured due to wind storms during the construction of the skyscrapers. For example, during the opening of the TD center, the building was highly windy such that climbing ropes had to be incorporated up the stairs for people’s safety. Similar cords are also a common feature along Front Streets to impede pedestrians from being blown away.
More Skyscrapers, More Channeling or Corner Vortexes
With other safety techniques being implemented in Toronto, climbing ropes are no longer required. Ryerson University tests the subsonic wind tunnel regarding how tall buildings and wind interact. They research how structures alter wind patterns for people on the streets and offer advice on the recommended construction methods for skyscrapers. Tall buildings typically cause the following problems in Toronto:
- Down-Washing – Happens when winds hit buildings, slide down the facades, and spin to the surface at incredibly high speeds.
- Channeling – Happens when winds are funneled through narrow spaces between buildings, which accelerates the speeds.
- Corner Vortex – occurs when winds hit building corners with sharp edges that cause them to turn up at the angles.
One of the solutions to these problems was the addition of podiums and awnings to the building’s designs. In case the winds hit the top of these skyscrapers and channeled downwards, podiums help stop their momentum before hitting the ground on the streets, diverting them back upwards.
According to Lorna Day, director of Toronto’s Urban design, some streets are windier than others due to the presence of towers in specific locations. Various regulations help prevent risky skyscrapers from going up, but sometimes, the modifications required to be done to address the wind problems can’t be achieved. By the time the Urban design department receives the required information, it’s usually too little too late to redesign individual buildings.
Implementation of the Wind Test Regulations
In Toronto, 12-storeys towers and above require proper wind assessment. The city is updating these wind laws since they are over twenty years old. Toronto’s definitions of comfort while on the streets have changed. Today, street-level comfort is a big concern for most people in Toronto as the city continues growing vertically. In Toronto alone, there are approximately four hundred proposed buildings ready for construction. Hence, it’s a shared responsibility for the city management and developers to come up with wind solutions.
If you have been wondering Why is Toronto so Windy, there you have it. From topography, tall skyscrapers, temperature, air pressure, centripetal acceleration, and earth’s rotation, these factors cause windy conditions in Toronto. There may be other factors that we have not covered in this post that you can research and find more information. However, these are the leading causes of windy weather in Toronto.