On long stretches of lingering fog or days when the mountains are warmer and sunnier than down at sea level, a temperature inversion is often to blame. It is a common occurrence here in Vancouver ...

A temperature inversion occurs when a layer of warmer air sits over a layer of cold air. Keep in mind, warmer air rises. So, if the cold air near the ground warms up and tries to rise, it ...

Sudbury Sudbury temperature inversion traps fumes in urban areas CBC News · Posted: Jan 13, 2015 10:51 AM PST | Last Updated: January 13, 2015 ...

A temperature inversion is now in place. Under an inversion, moisture can build up, causing clouds and fog. If the inversion is strong enough, dense fog can become a hazard.

However, a temperature inversion means it's warmer higher up in the atmosphere, which keeps the air closer to the surface trapped and stagnated.

As of 1 p.m., the temperature was in the upper 30s on the mountain, and down near the base of Mt. Hood Meadows, it was in the mid-40s. That temperature inversion is fixing itself.

An inversion happens when the temperature increases with height, the Met Office said. "This often happens in areas of high pressure, where the air high up often sinks towards the ground," it said.