David Chapman had his first memorable brush with wild weather when he was only three years old.
There was a clap of thunder, and the power went out. “I asked my mom, what made the lights go out? She said, ‘Lightning,’” Chapman said.
When he was eight, other kids were reading Berenstain Bears. “I was reading about mesocyclones.”
The clincher happened when he was 12, and he saw a tornado for the first time.
“I told my friends I was going to become a stormchaser,” Chapman said.
Actually, it is more accurate to say he is a sky watcher — fascinated by all kinds of weather phenomena, from clouds to the aurora borealis — as well as a professional photographer, videographer and speaker.
Chapman was at the Bradford West Gwillimbury Public Library on Wednesday night, sharing his experiences and his enthusiasm for wall clouds, downbursts and wild weather, including the lightning that first sparked his interest.
Chapman’s remarkable videos showed the typical lightning stroke downwards from a cloud, revealing its branching details and multiple hits. The videos also captured examples of upwards lightning — clusters of strikes that appear to be associated with operating wind turbines, and the deadly “bolt from the blue.”
The expression is based on fact: lightning generated at the top of a thunderhead can actually strike far from the storm. It is positively charged, which makes it more powerful than the run-of-the-mill lightning strike — which is why, Chapman said, it’s best to watch storms from shelter, as soon as a thunderhead appears.
The most common form of severe weather in Ontario is the gust front, Chapman said.
This is the downdraft side of the storm, where cold air descends suddenly and meets warmer, rising air. Often accompanied by a distinctive flat shelf cloud, gust fronts can range from just a few dozen kilometres to thousands of kilometres long, generating rain, hail and powerful winds.
Those winds can reach upwards of 100 km/h and hit with tornadic force, but they are level and lack the rotational spin of tornadoes.
“As a storm chaser, you really try to stay out of the storm,” Chapman said.
All that rain, wind and hail is dramatic, but it doesn’t make for clear images. It can be particularly difficult to film tornadoes in Ontario, he noted, because so often “it can actually be rain-wrapped.”
In many instances it is only by checking the storm path and damage that a tornado can be confirmed.
Right now, he said, the province still seems to be outside tornado alley, with only 12 to 14 tornadoes reported each year. What has changed is the level of reporting — with better technology, and more people watching, it’s easier to confirm that a tornado has touched down.
Chapman used his images to trace the evolution of a thunderstorm and tornado. All thunderclouds begin with the same thing — a strong updraft of warm, moist air. As it rises, the air cools, causing water vapour to condense and form a cloud.
“Basically, they all start out as a small cumulus cloud,” he explained. But when conditions are right, the rising air can punch through to a tremendous height — 6.7 km in a typical storm, or 13.4 km in the kind of rotating supercell that breeds tornadoes.
Funnel clouds, hanging down from the storm, are more common than tornadoes. Few supercells in Ontario have the right balance of rotation, powerful updrafts and downdrafts, and usually the clouds lift and the energy dissipates before a tornado can touch down — but not always.
Chapman’s most dramatic video condensed a 41-minute chase into three minutes, showing the formation and dissipation of a tornado.
For Chapman, it was “the perfect storm… It gave us so much information, but didn’t hit any houses.”
He was asked why the sky can turn a sickly green before a tornado or severe storm.
“Generally it means hail, that there’s a fair bit of ice up there,” Chapman said. Hail forms when there is a strong updraft, and the ice particles scatter the light, creating the green colour.
If the sky turns that aqueous green, he said, “it’s always just best to go into the basement — ride it out.”
But what if one is in a vehicle and sights a tornado? Chapman noted that Environment Canada advises getting out of the vehicle and taking shelter in a ditch or other low point, since the strong, whirling winds of up to 450 km/h can flip or even lift cars and trucks to great height.
Chapman said he prefers to stay in his vehicle, which at least provides some protection from flying debris, and watch which way the tornado is moving.
Choose an object in front of the storm, he said: if the tornado moves to the right or left of the object, it is moving away, and safe to stay where you are. If the funnel appears to get bigger, the storm is moving toward you — and it’s time to turn around and drive away, preferably in a southerly direction, to get behind the storm.
Chapman can work up to 70 hours a week, following his passion.
“I’ve gone 36 hours straight — from storms, to Northern Lights,” he said.
And although his presentation was about storm chasing in Ontario, he said, “I’m here not to teach you how to storm chase, but to show you the clouds.”
