The formation of freezing fog

We’re no strangers to fog in Atlantic Canada.

The presence of fog one morning recently didn’t seem like anything out of the ordinary. However, some areas were experiencing freezing fog. I told my co-workers about the freezing fog and one of my colleagues had never heard of it.

So, what is freezing fog? Let’s look first at how fog develops. Fog forms when the air cools and water vapor condenses to form water droplets. This can happen in several ways and depends on what kind of fog you’re experiencing.

Freezing fog is like regular fog. However, if the temperature is at or below freezing, the liquid water droplets are supercooled and freeze instantly on exposed surfaces. This can coat anything, from trees, to grass, to fences.

But freezing fog can also be dangerous as it can cause black ice to form on roadways. So, the next time you’re seeing fog and the temperature is below freezing, it’s more than likely freezing fog.

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DID YOU KNOW?

Newfoundland is considered the foggiest place in the world.

According to the Guinness Book of World Records, the Grand Banks experience more than 200 foggy days, the most anywhere in the world.

This is because the cold Labrador current meets with the warm Gulf Stream from the south.

St. John’s, N.L. and Halifax, N.S. are among the foggiest cities in Canada, according to Environment Canada.

Allister Aalders is a weather specialist with SaltWire Network. Reach him at allister. aalders@saltwire.com