Today is World Oceans Day. In 2010, the United Nations, at the urging of Canada, declared June 1 to 8 as World Oceans Week. The goal is to educate us about the importance of protecting our waterways, watersheds and ocean waters.
Did you know
- Everyone in the world lives on a watershed.
- Oceans generate 80 per cent of our oxygen.
- Oceans provide medicine and food
In Atlantic Canada, the ocean is a very big part of our daily lives. Sometimes I’m surprised at how little we think about its impact on our weather. Earlier this week I tweeted about how lovely it was in Halifax. Someone commented on the fact that the south wind was cool. He wondered why, since a south breeze usually implies some heat.
is true, over land, but if you live along one of our south-facing coastlines, the “sea breeze” is not warm in the spring.
A sea breeze describes a wind that blows from the ocean towards land. Across our region, this breeze occurs most often in the spring and early summer because of the greater temperature differences between the ocean and nearby land, especially in the afternoon when the land reaches its maximum heat from the sun.
During the day, the sun heats up both the ocean surface and the land. Water is a good absorber of energy from the sun. The land absorbs much of the sun’s energy as well. However, water heats up much more slowly than land and so the air above the land will be warmer compared to the air over the ocean. The warm air over the land will rise throughout the day, causing low pressure at the surface. Over the water, high surface pressure will form because of the colder air. Mother Nature is always trying to create a balance; the wind will, therefore, blow from the higher pressure over the water to lower pressure over the land, causing the sea breeze. The sea breeze strength will vary depending on the temperature difference between the land and the ocean.
At night, the roles reverse, especially under clear skies; the air over the ocean stays warmer than the air over the land. The land loses heat quickly after the sun goes down and the air above it cools too. This causes the low surface pressure to sit over the ocean during the night and the high surface pressure to move over the land. This small temperature gradient between the ocean surface and the nearby land at night allows the wind to blow from the land to the ocean, creating the land breeze.
I’ve just described a typical spring set up; the reverse occurs in the fall when our ocean temperatures are slow to cool but the land releases heat to the fall air.
Understanding the ocean’s impact helps us understand our weather.
I’d like everyone to take action to preserve, conserve and protect our magnificent oceans. The future of our planet is in our hands.
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Cindy Day is the chief meteorologist for SaltWire Network.