FAA Instrument Flight Instructor (FII)WeatherMedium
During the afternoon at a coastal airport, a pilot notices the surface wind consistently blowing from the ocean toward the land. What is the most likely cause of this wind pattern?
- ALand heats faster than water during the day, creating lower pressure over land that draws air in from the sea
- BA cold front passage has produced a permanent wind shift from offshore to onshore
- CKatabatic drainage winds are flowing from higher terrain toward the coastline
- DWater heats faster than land during the day, forcing air to flow from land to sea
Show answer & explanationAnswer & explanation
Correct answer: A. Land heats faster than water during the day, creating lower pressure over land that draws air in from the sea
During daytime, land heats more quickly than water due to its lower specific heat, causing air over land to warm, expand, and rise, creating a local area of lower pressure. Cooler, denser air over the water flows inland to replace it, producing the typical afternoon sea breeze.
Why the other options are wrong
- B. A cold front passage is a synoptic-scale event and does not explain a routine daily onshore wind pattern.
- C. Katabatic winds are downslope drainage winds, typically at night, unrelated to this daytime coastal pattern.
- D. This reverses the actual mechanism; land, not water, heats faster during the day.
Sea Breeze
A sea breeze is a local wind that blows from the sea toward the land during the day, caused by land heating faster than water and creating a local pressure gradient that draws cooler air inland.
- Occurs during the day due to differential heating
- Land has lower specific heat, warms faster than water
- Cooler air flows from sea to land at the surface
- Land breeze is the reverse, occurring at night
Memory trick: Daytime: sea breeze blows in; nighttime: land breeze blows out