Canada Science and Technology Museum
3 things you should know about the science behind the diversity of Canada's winter precipitation, the April 2024 solar eclipse and how to safely watch it, and how the new methods of bioponics can make hydroponic agriculture organic
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Feb 16, 2024
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Canada Aviation and Space Museum
Canada Agriculture and Food Museum
Meet Renée-Claude Goulet, Cassandra Marion, and Michelle Campbell Mekarski.
They are Ingenium’s science advisors, providing expert scientific advice on key subjects relating to the Canada Agriculture and Food Museum, the Canada Aviation and Space Museum, and the Canada Science and Technology Museum.
In this colourful monthly blog series, Ingenium’s science advisors offer up three quirky nuggets related to their areas of expertise. For the February edition, they tell us why there are so many different forms of winter precipitation in much of Canada, how solar eclipses come about and why safety comes first when observing them, and how a new form of agriculture called bioponics makes organic certification of hydroponics possible.
From Snow Flurries to Freezing Rain: Exploring the Diversity of Canadian Winter Precipitation
For many of us who endure Canadian winters, the type of precipitation we get — whether it's rain, freezing rain, sleet, or snow — determines how we dress, how we spend time outdoors, and how annoying our commute is going to be.
At -5°C, we might experience any of these forms of precipitation, leading to the natural question: why? The simple explanation is air temperature. The slightly more complicated answer is the air temperatures of each layer of air that the precipitation falls through on its journey from cloud to ground.
Photo Credit
In winter, the type of precipitation we get—whether it's rain, freezing rain, sleet, or snow—depends on the temperature of the air it travels through as it falls.
Snow: Most winter precipitation starts out as snow. This process typically occurs in clouds where water vapour sticks to tiny particles, such as dust or pollen. At sub-zero temperatures, the water freezes into ice crystals. As the crystals collide and stick together, they grow into the large, intricate structures we recognize as snowflakes. If the air temperature stays below freezing the whole way from cloud to ground, the snowflakes fall to the ground as snow.
However, air is not always the same temperature throughout the atmosphere. Things get a bit more complicated if the snow falls through zones of warm and cold air as it falls to the ground. How much warm air snowflakes fall through determines if they become rain, freezing rain, or sleet.
Rain: If the atmosphere is below freezing in the clouds, but warm the rest of the way down, then snowflakes will melt and turn into rain. Even if the air near the ground is freezing, the rain may not have time to get cold enough to freeze, and you can end up with rain even when the temperature outside is a little below freezing.
Sleet: If snowflakes fall through a thin layer of warm air, they will partially melt. If they then fall through a thick layer of freezing air, these slushy drops refreeze and reach the ground as frozen drops that bounce on impact. These are known as ice pellets, or sleet. Depending on the intensity, sleet can accumulate on the ground in piles of frozen pellets.
Freezing rain: If snowflakes fall through a thick layer of warm air, they melt completely into rain. If the liquid rain drops fall through a thin layer of freezing air just above the surface, they will cool down a bit, but not enough to freeze and turn into sleet. Instead, when the water droplet reaches the surface of the Earth and collides with a cold object (such as a car, street, or tree), it freezes immediately and turns into ice. Instead of ice pellets, freezing rain creates a sheet of ice on the ground, trees, power lines, and other objects. A small amount of freezing rain can cause dangerous travel conditions, while large amounts (called an ice storm) can cause significant damage.
As we navigate Canada’s unpredictable winters, armed with a bit of meteorological insight, we can better adapt to the ever-changing conditions and embrace the beauty and challenges each form of precipitation brings. Just remember to check with your local meteorologist before heading outside.
By Michelle Campbell Mekarski
2024 Solar Eclipse: What’s happening and how to watch safely
On April 8, 2024, a partial solar eclipse will be visible across most of the North American continent, while lucky spectators along the path from Mexico to the southern parts of Ontario, Quebec, and through central New Brunswick and Newfoundland will experience a total solar eclipse.
Photo Credit
A solar eclipse very close to totality, from 2017. In Ottawa this year, this is what our maximum partial eclipse will resemble: a thin crescent still peeking around the Moon with the Sun’s wispy corona coming into view.
A solar eclipse is a natural phenomenon that occurs when the Moon passes between the Sun and the Earth, the Moon’s shadow is cast onto the Earth when the three bodies align just right. As the Moon’s orbit is elliptical and inclined relative to Earth’s, this is not a common occurrence. Depending on the Moon’s distance from the Earth, and your relative viewing position, there are a few different types of solar eclipse:
Total Solar Eclipse: The Moon completely covers the Sun, creating a temporary night for a few minutes, where the Sun’s corona is visible.
Partial Solar Eclipse: Only a portion of the Sun is obscured, leading to a partial dimming of sunlight.
Annular Solar Eclipse: The Moon covers the Sun’s centre, but doesn’t cover it entirely, leaving a ring of sunlight, a.k.a. “ring of fire” around the Moon.
The view from Ottawa: In the capital, we will experience a partial solar eclipse where the Moon will start obscuring the Sun at 2:11 p.m. ET, will reach a maximum coverage of a whopping 98% totality at 3:25 p.m., and finish at 4:35 p.m. ET. Click here to find out eclipse timing in your area.
Photo Credit
From left to right, example images of a partial solar eclipse, an annular solar eclipse, and a total solar eclipse.
Safety First: Observing Solar Eclipses
Do not look directly at the Sun without eye protection!
On a regular sunny day, we instinctively or reflexively turn our eyes away from the brightness of the Sun. Looking directly at the Sun can lead to permanently damaging your eyes and possibly causing blindness. The Sun is still far too bright for our eyes during an eclipse as well. A solar eclipse is only safe to view without protection during totality, when the Moon completely blocks out the Sun for a few minutes. If you are viewing a partial eclipse, as is the case in Ottawa – at no time will it be safe to view the April 8th eclipse without eye protection.
Protection options:
- Solar viewing glasses: Special purpose solar filters or glasses certified to meet the ISO 12312-2 international safety standard, that blocks out the majority of the light coming from the Sun. Regular sunglasses or homemade filters are not sufficient.
- Solar filters for telescopes, binoculars, or cameras: Attach an ISO 12312-2 certified solar filter to all optical devices to prevent concentrated sunlight from entering and damaging your eyes.
- Pinhole projector: Watch the eclipse indirectly! You can construct a pinhole projector by poking a small hole in a piece of paper or cardboard, and letting the sunlight project through the hole and onto a surface. Simply look at the projection rather than at the Sun. You can also use something that already has small holes in it like a colander or spoon.
We invite you to come to the Canada Aviation and Space Museum on April 8, 2024. We will be offering free eclipses glasses with your museum pass while supplies last, and help you design your own pinhole projector, make crafts, and more!
Helpful Resources:
Interactive map view of the path of the April 8th solar eclipse
Animated view of the April 8th eclipse on the Earth
Royal Astronomical Society of Canada
By Cassandra Marion
Bioponics: paving the way to organic hydroponics
If you've eaten cucumbers, tomatoes, bell peppers, green beans, eggplants or strawberries in winter in Canada, chances are they were grown hydroponically in a greenhouse. That is as long as they aren't certified organic. That’s because Canada's organic standards prohibit food grown through hydroponics from being certified organic. But a new approach to hydroponic culture, called bioponics, is helping to usher in a new era where soilless farming could fit within the principles of organic agriculture. Let's explore!
Photo Credit
Lettuce growing in a hydroponics greenhouse
Hydroponics is a form of controlled environment agriculture. This means growing crops under cover, such as in a greenhouse, which allows growing conditions like temperature, air composition, lighting, and pests to be closely monitored and controlled. In this type of system, plant roots grow in rockwool, clay pellets, vermiculite, or another soilless medium. The nutrients the plants need to grow are dissolved in water and fed to the roots by recirculating irrigation systems, which greatly reduces water use compared to growing in the field. Because growers can adjust nutrients and water chemistry to the specific needs of plants, often through automation, they can grow more food per plant, and conserve nutrients. It also allows food to be grown year-round in urban areas, and where the climate limits agriculture.
Because Canadian organic standards require that food be grown in living soil and they only allow the use of organic sources of fertilizer (manure, compost, seaweed), hydroponics can't be organic, even if it meets all other requirements. This is in big part because current systems use mineral fertilizers. These come from mining and energy-intensive chemical processes. So, is there a way to replace these with organic fertilizers instead? That's what bioponics aims to do, with a living ecosystem approach.
To align with organic production principles, bioponics closes the nutrient loop by using microbes to "digest" liquid or solid plant and animal waste, converting tied-up nutrients into forms plants can use again. In order to do this in a hydroponic system, innovators have added on something called a biofilter — a place for microbes to live, eat, and reproduce. Farmers feed the microbes, and the microbes feed the plants. In this type of system, humans play a bigger role than in conventional hydroponics, since it’s more like taking care of an animal. Farmers need to closely monitor and adjust conditions, as well as levels of nutrients released by the microbes over time to keep things balanced. Since fertilizers for bioponics can be made from locally available material, this can help recycle organics collected from the local communities. It could also make soil-less culture more feasible and economical in places where it is difficult to access commercial fertilizers, such as remote northern locations.
Canadian organic norms were recently revised in 2020 and are currently in another round of revisions for 2025. Part of the proposals for changes include allowing hydroponics, and adding the definition for microbial fertilizer. If accepted, these changes could pave the way for future proposals to include bioponics as an accepted way of growing food organically.
To face the challenges of soil loss, growing urbanization, and the effects of climate change, we need a diversity of solutions, including those that allow us to produce a range of foods close to where people live, and with the locally available resources. This feeds into food sovereignty, as it allows communities to be in charge of their own food supply. While not without its challenges — rising energy costs, inflation, lack of specialized labour — soilless, indoor growing offers a sustainable path to food security from coast to coast to coast. Perhaps in the future, Canada will widen its definition of organic agriculture to include these new ways of growing, thereby contributing to meeting the demand for locally grown organic food.
By Renée-Claude Goulet
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Michelle Campbell Mekarski, PhD
As the Science Advisor at the Canada Science and Technology Museum, Michelle’s goal is to bridge the gap between the scientific community and the public — specializing in making science and technology engaging, accessible, and fun. Michelle earned a PhD in evolutionary biology and paleontology and has many years of experience developing and delivering science outreach activities. When away from her job at the museum, she can be found teaching at the University of Ottawa or Carleton University, digging for fossils, or relaxing by the water.
Cassandra Marion, PhD
Cassandra is the Science Advisor for the Canada Aviation and Space Museum. She has a PhD in geology and planetary science and exploration. Her research is focused on meteorite impact craters in the Canadian Arctic. She has more than a decade of experience in education and public outreach, developing and delivering science programming. She is dedicated to sharing her passion for Earth and planetary sciences with communities near and far, and improving science literacy in Canada.
Renée-Claude Goulet
Renée-Claude Goulet is the Science Advisor at the Canada Agriculture and Food Museum, with over 15 years of experience in science communication. At the Museum, she develops exhibitions, educational programs, and resources that explore the science and innovation behind agriculture and food production. An Ontario Certified Teacher with a BSc in Biology and a BEd in Sciences, Renée-Claude is passionate about making complex topics accessible and engaging for all audiences.
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