What made for so much lightning over Ottawa on Tuesday night?

Lightning over Ottawa during Tuesday night's storm. Photo by Tony Caldwell /Postmedia

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Mother Nature’s (somewhat) impromptu lightning show was the topic of the day on July 15 for some Ottawa-Gatineau and Algonquin area residents who captured and shared the colourful flashes on social media.

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While the bulk of the lightning strikes happened closer to 10 p.m., Environment Canada meteorologist Kate Leclerc says the thunderstorms lasted for hours.

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Between 10 p.m. and 2 a.m., Ottawa witnessed widespread strikes. As entertaining as they may have been for some, the flashes were intense, consecutive and fierce.

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So, what’s really behind the lightning strikes?

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On Tuesday, Environment and Climate Change Canada had issued an expansive “yellow warning” alert for heat and a severe thunderstorm in Ottawa. Maximum temperatures were expected to reach up to 36 C.

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Tuesday wasn’t as hot as what the weather agency had predicted, but it was certainly hot enough. Temperatures hovered just above 30 C, with humidity making Tuesday feel like 42.

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The drastic drop in temperature (from day to night) created “leftover energy”, which resulted in Ottawa’s prolonged overnight lightning strikes, according Connor Mockett, a storm chaser and photographer based out of Winchester, about 40 minutes south of Ottawa.

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“Once night came and the temperature dropped from a really hot day, storms were able to form,” Mockett said.

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Lightning over Ottawa during Tuesday night’s storm. Photo by Tony Caldwell /Postmedia

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The explanation was simple.

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Mockett pointed to the Convective Available Potential Energy (also known as CAPE). It’s a meteorological measure of the atmosphere’s instability and the amount of energy that’s available to fuel developing thunderstorms.

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When there’s a lot of that CAPE energy in the atmosphere, that often means you’re going to have a lot of lightning.

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“Yesterday there was about 3,000 to 4,000 CAPE in Eastern Ontario,” he says, “which is really high for here.”

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Recent smoke may have lessened impact of lightning

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Earlier in the week, on Sunday, the national weather agency had issued another yellow warning as smoke from Northern Quebec forest fires made their way to Ottawa.

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This decreased air quality, and no one in Ottawa was really thrilled about it.

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While there are fires currently in Northern Quebec, it’s actually the fires in the Western Ontario region that are feeding the smoke over Southern Ontario, according to Leclerc.

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Regardless, she says the smoke definitely impacted the severity of Tuesday’s thunderstorms.

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That’s because the thick layer of smoke in the air worked to inhibit the sunlight and moisture from reaching and feeding into the thunderstorm and lightning.

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The science behind it may at times be hard to predict, but Leclerc says the thickness of the air due to smoke is known to impact the frequency of lightning.