Dust Devils Explained: How these weather phenomena sparked fires at Lake Somerville Sunday

SOMERVILLE, Texas (KBTX) - Over the weekend, reports came in from the Rocky Creek Volunteer Fire Department that wildfires were reignited at Lake Somerville by a runaway weather system -- a dust devil.

Dust devils, which are often noticed for their likeness to the much more severe tornadoes, are a common weather occurrence during the summertime in Texas. They are formed by pressure differences created by daytime heating. The sun does not warm every area at the same rate, creating little “pockets” of warmer air surrounded by cooler air. Warm air is less dense, so it rises into higher parts of the atmosphere -- creating an area of lower pressure where the air warms faster. The surrounding “cooler” air then moves and spirals into the lower pressure, creating a circulation.

The circulation then stretches upwards as the warm air rises, causing wind speeds to increase. This process is similar to the formation of a tornado. The stretching of the circulation is what causes the windspeeds to climb, and gives both dust devils and tornadoes their signature “spin”.

This particular dust devil at Lake Somerville picked up embers from a previous burn scar and lofted them over 100 yards away, igniting a brand new fire. Another fire was started by a lightning strike from a storm over the weekend.

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