How the ocean influences our weather
The stormy weather that hit the UK last week was caused by the tail end of Hurricane Gonzalo. We have all covered, at some point in the past, how global weather is formed but most of us are probably pretty rusty on the facts. As my background and passion lies in marine biology, I am going to focus this article on how the world’s oceans help produce and influence the weather we experience.
The ocean plays a crucial role in influencing the earth’s climate due to it’s ability to absorb, store and transport the sun’s heat. When the water temperature is higher than the air temperature, the ocean transfers heat to the surrounding air, creating a low pressure air mass. If the air temperature is warmer than the ocean, then heat is transferred the other way, creating a high pressure air mass. These air masses influence the direction of wind, as air flows towards areas of low pressure.
As well as transferring heat between the ocean and air, water molecules are also transferred. Especially near the equator, the sun’s heat causes water to evaporate, increasing the humidity of the surrounding air. This creates storms and rain, that can be transported away from the equator by the trade winds (easterly winds).
Moving away from the equator, the heat absorbed by the surface water is transferred around the world by ocean currents, regulating global temperature on both short and long-time scales. The large ocean currents are created by the interaction of surface winds, salinity and temperature gradients, tides and the earth’s rotation. The UK’s mild weather is caused by the Gulf Stream, which brings warm water passed our coastlines from the Gulf of Mexico.
Hurricanes, such as Hurricane Gonzalo, occur when ocean water warmer than 26.5 Degrees Celsius evaporates. The warm, moist air rises in the atmosphere creating an area of low air pressure below it. This draws in cooler air that rotates around the centre of low air pressure, creating winds with increasing intensity.
The interactions between the atmosphere and the ocean that help to create our climate are very complex and there is still masses of interactions that we do not fully understand. This is one of the reasons why scientists are finding it so hard to predict what may happen to our global weather in a future with climate change.
How stuff works website
National Geographic website
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