Sea, land and lake breezes
Local wind (AWH 10.6): small-scale circulation from day/night heating and cooling of ground, independent of synoptic pressure pattern.
- Cooler, denser surface: builds higher pressure.
- Warmer, less dense surface: builds lower pressure.
- Low-level wind flows high to low.
- Coriolis negligible: too small and short-lived to deflect. Wind blows straight cool/high to warm/low, not curved like geostrophic wind aloft.
- Easiest to spot when synoptic wind is weak.
| Breeze | When | Direction | Cause | Weather | Cite |
|---|---|---|---|---|---|
| Sea | Day | Onshore (sea to land) | Land heats faster than water: lower pressure over land; air rises over land, sinks over water | Cloud may build over land, dissipate over water | AWH 10.6.1 |
| Land | Night, early morning | Offshore (land to sea) | Land cools faster than water: higher pressure over land | Usually weaker than sea breeze; cloud and precipitation form over water | AWH 10.6.2 |
| Lake | Afternoon | Large lake to shore | Lake surface colder than land | Common on Great Lakes, mainly spring and summer; easiest in light synoptic wind | AWH 10.6.3 |
Sea breeze front (AWH 10.6.1.1): leading edge of cooler, moister marine air pushing inland.
- Marked by wind shift and extra cumulus (absent if lifted air is dry or stable).
- Convection usually too shallow for precipitation.
- Can still be the lifting mechanism for showers or thunderstorms.
Trap: swapping the pair: sea breeze onshore by day, land breeze offshore by night.
References
- FAA Aviation Weather Handbook (FAA-H-8083-28) 10.6
- FAA Aviation Weather Handbook (FAA-H-8083-28) 10.6.1
- FAA Aviation Weather Handbook (FAA-H-8083-28) 10.6.1.1
- FAA Aviation Weather Handbook (FAA-H-8083-28) 10.6.2
- FAA Aviation Weather Handbook (FAA-H-8083-28) 10.6.3