How Ocean Breezes Form: Sea Breeze & Land Breeze Cycle

The Daily Rhythm of Coastal Winds

Ocean breezes are driven by differential heating of land and water. The cycle has two phases:

Sea Breeze (Daytime)

1. Solar heating: Land heats faster than water (lower heat capacity).
2. Temperature gradient: Land surface warms → air above warms, expands, rises.
3. Pressure gradient: Low pressure over land; higher pressure over cooler ocean.
4. Air flow: Cool, dense ocean air moves inland → sea breeze (onshore).

Peak: mid-afternoon. Speed: 5–20 knots. Can penetrate 10–50 km inland.

Land Breeze (Nighttime)

1. Radiational cooling: Land cools faster than water (higher emissivity).
2. Reversed gradient: Land cooler → air denser → high pressure over land.
3. Air flow: Air moves from land to ocean → land breeze (offshore).

Weaker than sea breeze (2–8 knots). Peaks before dawn.

Influencing Factors

• Temperature contrast (land vs. sea).
• Coastal topography (mountains channel/block flow).
• Synoptic wind (strong prevailing winds can override).
• Latitude/season (stronger in tropics/summer).

Impacts

• Moderates coastal temperatures.
• Triggers afternoon thunderstorms (sea breeze convergence).
• Affects sailing, aviation, pollution dispersion.