FAA Airline Transport Pilot (ATM)Meteorology and Weather ServicesMedium
A pilot departing a coastal airport on a calm, clear afternoon notices low cumulus clouds forming near the shoreline and a distinct wind shift from offshore to onshore as the flight approaches the coast. What phenomenon is most likely responsible for this wind shift?
- AA squall line associated with an approaching cold front
- BA land breeze forming due to nighttime radiational cooling
- CA katabatic wind draining down from higher terrain
- DA sea breeze front caused by differential heating between land and water
Show answer & explanationAnswer & explanation
Correct answer: D. A sea breeze front caused by differential heating between land and water
During the day, land heats faster than water, creating lower pressure over land. Cooler, denser marine air flows onshore to replace the rising warm air, forming a sea breeze front, often marked by a line of cumulus clouds and a wind shift near the coastline.
Why the other options are wrong
- A. Squall lines form ahead of cold fronts and are unrelated to calm, clear coastal afternoon conditions.
- B. Land breezes occur at night when land cools faster than water, producing offshore flow, the opposite of this scenario.
- C. Katabatic winds are driven by cooling on elevated terrain, not coastal heating differences.
Sea Breeze Front
A local wind boundary formed by differential heating of land and water, where cooler marine air flows onshore during the day to replace rising warm air over land.
- Occurs during daytime due to land heating faster than water
- Often marked by cumulus cloud lines and low-level wind shift/turbulence
- Reverses at night as a land breeze when land cools faster than water
Memory trick: 'Day breeze blows in from the sea, night breeze blows out to sea'