What Causes a Sea Breeze?

My first solo offshore passage began with sunshine, gentle breezes and easy sailing. But there was nothing gentle about my return to land at day’s end.
Author:
Updated:
Original:
Sea-Breeze

My first solo offshore passage was marked by sunshine, gentle breezes and easy sailing. But there was nothing gentle about my return to land. Tempestuous head winds stilted my landfall as my little boat crashed through waves. By the time I was nearing the entrance to the harbor, the sky had turned to night and there was no light to guide me through the channel. I was tense as Daphne raced between the rows of channel markers, inconspicuous in the night.

Safe in the harbor, I breathed a sigh of relief and decided that my next landfall would be in the daylight. But it wasn’t just the darkness that made the landfall difficult that night. It was equally the strong headwinds. So, I also thought it would be best to make landfall with favorable winds and it just so happens that a sea-breeze often brings favorable winds for making landfall in the day.

A sea breeze is a local wind, independent of global wind patterns such as the Trade Winds or Westerlies. But like the Westerlies and most winds, they are named for the direction from which they flow and the sea breeze flows from the sea toward the land. Sea breezes affect the area along a coast and can extend as far as twenty miles offshore. Like all winds, a sea breeze is formed as a result of a change in temperature and air pressure.

The primary cause of all winds, global or local, is the difference in air pressure. Air will naturally flow from areas of high pressure to low pressure. Think of a balloon at a birthday party, for example. A balloon filled with air has higher pressure inside the balloon than the air surrounding it. When the balloon’s knot is untied and the balloon is released, the air quickly rushes out.

A sea breeze is created when a low pressure forms over the coast. The sea has a greater heat capacity than land, meaning it requires more heat to change its temperature. Therefore, during the day, as the sun’s warm rays shine down on the earth, because of the difference in heat capacity, the land heats up faster than the sea. The air above the land also warms. Since warm air is less dense than cool air it begins to rise, leaving an area of low pressure just over the land.

The sea breeze is created when the cool air over the sea rushes in to fill the low-pressure region making a favorable wind for making landfall.

Another benefit of this cycle is that the warm air rising often forms puffy cumulus clouds over land. Out at sea, these clouds can be an indicator for the island destination you are looking for long before the island itself appears above the horizon.

Illustration by Teresa Carey

Read, Knowing the Land and Sea Breezes, by Connie McBride here

Related

DSC_5337-2

Boat Review: X-Yachts X4⁶

The Danish builder X-Yachts does not simply stick taller or shorter rigs and keels on the same hulls to create boats for both cruisers and racers, as some mass-production builders do. Nor is it content to build two distinct lines of cruisers and racers. Instead, the company has ...read more

Screen Shot 2020-09-18 at 1.18.36 PM

Harken Changes Hands, Stays in the Family

. In a video posted yesterday, Peter Harken cheerfully announced that his company, Harken Inc., the trusted hardware brand bearing his last name, which was formerly owned by founders and their families has changed hands. The owners have sold their shares to employees—"passing ...read more

OceanRace

Newport Hosts The Ocean Race Summit on Ocean Health

Hundreds of participants from around the world tuned in yesterday for the latest installment of The Ocean Race's (formerly the Volvo Ocean Race) Summit Series, which aims to bring the best of ocean racing—leadership, resilience, tenacity, collaboration—to solving the ocean’s ...read more

sp360_fs5-024crop (1)

Highfield SPORT 360

The new 2021 SPORT 360 is the next generation of Highfield boats. Highfield is celebrating its 10th year in the market this year and in this relatively short period of time has now delivered over 30,000 boats to happy customers in 38 countries. Highfield is already the ...read more

sp560_drone-028crop

Highfield SPORT 560

The new 2021 SPORT 560 is the next generation of Highfield boats. Highfield is celebrating its 10th year in the market this year and in this relatively short period of time has now delivered over 30,000 boats to happy customers in 38 countries. Highfield is already the ...read more

Three Props 1772x1181

EWOL Propellers

Ewol propellers make maneuvering easier, increase sailing speed and increase cruising speed under power. EWOL adjustable pitch propellers are made of stainless steel alloys that represent the highest technology in terms of marine corrosion and galvanic corrosion resistance, ...read more

leadership-forum-LGBTQ-email-graphic

Tonight: US Sailing’s LGBTQ+ Panel

Tune in to the latest installment in US Sailing’s Diversity, Equity and Inclusion Series tonight at 7pm EDT. This week Kimball Livingston will moderate a panel of LGBTQ+ sailors who will share their personal and professional experiences as well as strategies for improving ...read more