The Wind and Your Beach Vacation

Many of us head to the beach because the weather there is a welcome change from towns and suburbs.  Temperature differences of 10 degrees or more are common between the shore and inland areas, despite equal amounts of sunshine and being on the same latitude.

Why is this so?  The primary factor that causes such temperature spreads is the cycle of sea and land breezes at the beach.  Data from the University of Illinois shows that large bodies of water like a lake or ocean are able to absorb more energy from the sun without warming up as the land does.  We also know that warm air rises because it is lighter and less dense than cold air. 

So, when the warm air over the beach rises, cooler air over the water rushes in to replace the void created by the rising air.  This rush of cooler air is what is commonly referred to as the sea breeze, which beachgoers can feel on their faces as it blows inland.  The sea breeze is an added benefit of the shore providing people with relief from the heat even before they get in the water.  We can enjoy the cooling effects of the ocean while we are still setting up our beach umbrellas! In contrast, just a few miles inland from the beach – and away from the cooling effects of the sea breeze – it’s often unbearably hot. 

At night the opposite is true, since the land cools off more quickly than the sea.  When the relatively warm air over the ocean rises, the cooler air over the beach rushes in to fill the void created over water.  Those who enjoy going for walks on the beach at night benefit from this land breeze blowing on their backs. 

Something else significant happens at the beach when the warm air rises.  If it rises high enough in the atmosphere, it leads to the formation of those puffy, fair weather clouds that meteorologists call cumulus clouds.  During the day, these cumulus clouds form just inland due to the sea breeze and just offshore at night because of the land breeze.  Under the right circumstances, these cumulus clouds can grow into cumulonimbus clouds and give rise to a thunderstorm.

Sea and land breezes only occur during times of calm weather.  When a larger weather system such as an area of low pressure or front is in the vicinity, their associated weather supersedes the small scale phenomenon that’s exclusive to the beach.