Spectacular roll cloud over Calgary, Canada

This dramatic weather phenomenon known as a roll cloud was captured over Calgary, Alberta, in Canada. The area was hit with severe weather that has caused widespread flooding in recent days, killing three people and forcing more than 100,000 people to flee their homes. Power outages in Calgary, Canada’s oil capital, could last months, rescue services were cited as saying in news reports. Credit: YouTube/Gry Elise Nyland.