How Does a Sea Breeze Form?

iStock
iStock

Walking outside during the summer can feel like walking into the bathroom after someone takes a shower. The muggy air gives you a great big unwanted hug, fogging up your glasses and forcing you into a gross and near-immediate sweat. If you're seeking relief, head to the beach: One of the great benefits of being near the coast is the cool afternoon breeze that takes the edge off of a hot summer day.

The sea breeze is a wind circulation that forms near the coast when there's a large difference between the temperature of the air over land and the temperature of the air over water. Land heats up much faster than water, so there's usually a big temperature gradient between, say, Mobile, Alabama, and the Gulf of Mexico just a few miles offshore.

The sea breeze process starts when warm, unstable air over the land begins to rise. This rising air creates a small area of lower air pressure at the surface. As part of Mother Nature's balancing act, cooler air over the ocean starts to rush toward land to fill the void left by the rising air. This eventually creates a circulation that continues for as long as daytime heating is present. As cooler air lingering over the water starts to spill inland, humidity goes up a bit, but air temperatures drop as much as 10°F to 15°F once it passes through. You don't need to be on the beach to reap the benefits of this phenomenon, either: A sea breeze can travel as much as 50 miles inland in some locations.

Aside from their cooling relief, sea breezes are most notable for the thunderstorms they can trigger near the coast. Sea breeze thunderstorms don't last for very long, but they can be a doozy, sometimes producing flooding rains, vivid lightning, and occasionally some damaging wind gusts.

Central Florida is famous for dealing with sea breeze thunderstorms almost every day during the warm season. The state's narrow shape allows two sea breezes—one from the Gulf of Mexico and one from the Atlantic Ocean—to collide with each other right in the middle of the peninsula. One sea breeze usually packs enough punch to fire up a hefty storm, but the lift created by two sea breezes colliding can trigger especially vivacious storms, as anyone who's ever visited Orlando's theme parks can tell you.

Once the Sun goes down and the sea breeze wanes, the opposite effect begins to take hold. Water holds onto its heat much better than the land, and as a result the air over the water usually stays warmer at night than the air over land. This disparity between land and sea causes what's known as a land breeze; it's the exact process that goes into a sea breeze, but blowing from the land out toward the sea instead. This process can also lead to thunderstorms, just close enough to the coast that anyone standing on the beach in the early hours of the morning can watch lightning flashing off in the distance.

Amazing Timelapse Shows Florida Sky Turning Purple Following Hurricane Dorian

Scott Olson/Getty Images
Scott Olson/Getty Images

Photographs taken of Hurricane Dorian's massive eye and the damage it caused in the Bahamas paint a picture of what it was like to live through the historic storm. But some of the most stunning images to come out of the event were captured after the hurricane had passed. As KENS5 reports, the time-lapse video below shows the sky over Florida turning a unique shade of purple in the wake of Hurricane Dorian.

Dorian skimmed the east side of Florida earlier this week, causing power outages and some flooding. The worst of the storm was over by Wednesday night, but the ominous purple clouds it left behind may have sparked concern among some Florida residents.

A purple sky following a hurricane is the result of a perfectly natural occurrence called scattering. The sky was super-saturated after Dorian arrived, and the moisture in the atmosphere refracted the light of the setting sun. Normally, only the longest wavelengths of light on the color spectrum are visible through the clouds—that's why sunsets often appear gold, pink, and orange.

Violet is the shortest wavelength on the spectrum, which means it's almost never visible in the sky. But the air's high dew point Wednesday night, combined with the dense low-hanging clouds, created the perfect conditions for a rare purple sky.

Locals who've lived through a few hurricanes may have recognized the phenomenon; the same thing happened after Hurricane Michael hit Florida last year.

[h/t KENS5]

See What the Eye of Hurricane Dorian Looks Like From Space

NOAA, Getty Images
NOAA, Getty Images

Hurricane Dorian has already caused damage on the ground, leveling houses and killing at least five people in the Bahamas earlier this week. For people who haven't seen Dorian's power up close, these pictures captured from space put the magnitude of the storm into perspective.

As Live Science reports, the photographs below were taken by European Space Agency astronaut Luca Parmitano aboard the International Space Station. They show the hurricane swirling over the Atlantic, its massive eye in clear view.

The storm has grown even more intense since it was photographed from space. According to a tweet from Parmitano on September 1, the pictures show Dorian as a tropical storm. By the time the system reached the Bahamas on Monday, September 2, it had upgraded to Category 5 hurricane with winds exceeding 185 mph. Dorian has since weakened to a Category 3, but that's still strong enough to cause significant destruction if it makes landfall over the U.S.

After preparing for a direct hit all week, it looks as though the southern U.S. may be spared from the worst of the storm. Projections now show Dorian hugging the Atlantic coast, starting off the coast of Florida and skimming Georgia, South Carolina, and North Carolina. The hurricane is still likely to drive powerful winds and storm surges along the east coast, so local governments are urging residents to take any necessary precautions and be prepared to evacuate if the order is given.

[h/t Live Science]

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