From sun dogs to snowpack, we answer some of your weather questions
We've received hundreds of questions from our CBC audience. Here are some of the most popular
CBC Alberta and Saskatchewan have teamed up for a new pilot series on weather and climate change on the Prairies. Meteorologist Christy Climenhaga will bring her expert voice to the conversation to help explain weather phenomena and climate change and how it impacts everyday life.
We've been covering weather and climate stories for a couple of months now with this project and every week we have given our audience the chance to pose questions related to climate change and weather. Since its start we have received hundreds of questions. So the time has come to turn the reins over to you.
This week we have picked a few of your questions to answer. And remember to keep those weather queries coming.
What is a sun dog?
If you look up at the sky on a clear and cold day you may notice a ring around the sun or a couple of bright spots next to the sun.
These are called sun dogs. But what are they?
Sun dogs form as a result of ice crystals in the atmosphere. These crystals can be higher up in the sky, or closer to the ground when the temperature is quite low.
As light from the sun passes through these crystals it refracts or bends. Depending how the crystals are oriented, you will see bright spots on either side of the sun or a halo running around it.
What are those ice pancakes on the river?
As rivers begin to freeze in late fall, the process isn't as simple as a sheet of ice forming.
The freeze happens in stages, with a visual treat known as pancake ice, those circular pieces of ice with what look like fluffy edges drifting on the river.
As the river begins to freeze, the ice crystals are loose and disorganized.
This ice is called frazil ice. As the frazil ice accumulates, it congeals to form masses which continually bump into each other due to the motion of the water. That gives them the raised edges and circular shapes.
Why doesn't the sun feel as strong in winter?
The Earth is tilted on its axis so the sun hits the earth at different angles depending on the season.
In summer, as the northern hemisphere tilts toward the sun, the rays hit Canada from a more overhead angle. The sunlight isn't spread over as large an area, meaning the energy is more concentrated, making it warmer.
The opposite is true in the winter as the hemisphere tilts away from the sun. When sunlight reaches the northern hemisphere it's at a lower angle, spreading out over a larger area. That means the sun will feel cooler.
Why is a winter snowpack important?
Though it can be a pain to shovel, snow will be crucial as our climate changes.
Snowpack, layers of snow that accumulate in winter, is an essential part of our water supply. It acts as a major source of moisture for our soil. In spring, melting snow supplies our freshwater, keeps our rivers running, and helps replenish our groundwater stores.
A heavier snowpack and slower spring melt can also slow the start of the fire season.
Stay tuned for a future story coming on how our changing climate will affect the snowpack and water supply in the Prairies.
Are chinooks only in southern Alberta?
Southern Alberta is often referred to as the chinook capital of Canada. These warm, dry winds often sweep across the province in winter.
A chinook occurs as air passes over the mountains. As that air rises it cools at a rate of 0.6 C per 100 metres. As it cools, water vapour condenses and we see rain and snow.
When the drier air rushes down the other side of the mountains, it is compressed and warms at a faster rate: at about 1 C per 100 metres.
Those warm winds rush into areas on the lee side of the mountains, sometimes warming temperatures by 15 C to 20 C in a short period of time.
Chinooks, also called Foehn winds or downslope winds, happen all around the world.
These types of warm and dry winds are common in California, where they are known as the Santa Ana winds.
What causes hoar frost?
If you are a photographer, the frosty winter mornings where trees are coated in frost are a dream. But is it always hoar frost?
Hoar frost, a type of feathery frost, forms under calm and clear conditions. It's similar to dew forming in warmer months, but the water vapour freezes onto cold surfaces, skipping the liquid phase all together.
If the frost layer is really thick and heavy, it is probably a result of rime ice, which forms under different conditions.
If you wake up to low visibility with ice fog and then see that coating on the trees, what you are seeing is rime ice. Those supercooled water droplets freeze onto trees and other objects and often look a little spiky.
Why are clear winter nights so cold?
While a clear, sunny day will feel warm in the summer, clear weather overnight can often mean the opposite, especially during the winter months.
We know after the sun goes down we lose that solar radiation and begin to cool. When it's a cloudy night, that heat is trapped, like a blanket. Clouds work to moderate overnight temperatures so we don't lose as much heat.
On a clear night, it's a different story. Without those clouds, that heat escapes into space, resulting in colder temperatures. That's why those clear winter mornings can be so crisp.
Our planet is changing. So is our journalism. This story is part of a CBC News initiative entitled Our Changing Planet to show and explain the effects of climate change and what is being done about it.
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