Smoke swirling in clouds over North America

No matter how ominous and dark gray rain clouds appear from Earth, they are invariably bright white in satellite photos from space. That’s why Canada has significant ash clouds. So they are not rain clouds, but smoke clouds from the massive wildfires that have been ravaging western Canada for over a month.

There are naturally dry areas in the rain shadow of the Canadian Rockies that increase wildfire risk in early spring. In a short time, the winter snow cover has already melted, but the herbs and trees have not yet sprouted. The dry forest floor is still bare and fragile.

This year, unfortunately, this fire-prone dry season coincided with unusual weather conditions, with extreme heat and strong winds. As a result, small, short-lived fires can grow into large flames that burn continuously for weeks. In May, more than one million hectares of forest were reduced to ashes.

The heat from the fire created strong rising air currents, sometimes called pyrocumulonimbus. These are characteristic mushroom- or anvil-shaped storm clouds, but mainly contain ice particles and soot particles instead of water vapor. These clouds push the smoke into the stratosphere, where it is carried by the jet stream.