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CINDY DAY: The answer is blowing in the wind

A blue sky day along the Holyrood Harbour, N.L.
A blue sky day along the Holyrood Harbour, N.L. - Rosie Mullaley

I made the move to Atlantic Canada 20 years ago. I had previously visited here and loved the people, the pace and, of course, the weather. As a trained meteorologist, I was very aware of the weather patterns that affect the East Coast, but reading about something and living it are quite different.

Cindy Day
Cindy Day

During my very first trip to the beach on a hot, sunny, early July afternoon, I experienced first-hand the cooling effect of the mighty North Atlantic. That lovely sea breeze can have you reaching for a jacket on a 30-degree day. Don’t get me wrong, it’s often quite welcome. I like to refer to it as natural air conditioning.

The sea breeze effect is fairly well understood, but I’m not sure that the reverse is.

During the day, the air over land is warmed by the sun and becomes much warmer than the air over the water. After sunset, on a clear night, the land releases that heat quite quickly. The ocean doesn’t warm up very much during the day and, by the same token, it doesn’t cool off very quickly at night. So, not long after sunset, the air over the ocean becomes warmer than the air over the land, especially early in the season.

Warm air is lighter than cold air and becomes buoyant. As the warmer air over the ocean rises, the relatively cool air that is sitting over land rushes out to fill the void left behind by the rising air. That flow of air from the land to the water is a reverse sea breeze, also known as a land breeze.

This land breeze explains why a summer stroll in a coastal community can be more enjoyable after the sun goes down.

You don’t need a weatherman to know which way the wind blows.” -- Bob Dylan

Cindy Day is the chief meteorologist for SaltWire Network.

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