Sea Breeze / Land Breeze Circulations

Sea/Lake Breeze Front is a boundary that is usually small and temporary but usually causes an abrupt drop in temperature as it passes (a distinct boundary between the cooler maritime air and the continental air it displaces). Whereas, just a sea/lake breeze is heating over the inland area which causes air to expand upward and diverge at higher altitudes. This creates a surface low-pressure area and the sea breeze flows inland from the sea.

Pressure starts out equal over the land and sea/lake but due to unequal surface heating. The land is warmer due to the ground absorbing heat faster than the sea/lake, resulting in the ground heating the air by conduction. The less dense, warmer air is rising and expanding thus increasing the upper-level pressure and creating divergence above while, decreasing the pressure over the land. Whereas, over the sea/lake, the cooler and denser air which has a relatively higher pressure resulting in low-level convergence due to the fact that air flows from high to low pressure (pressure gradient force).

The strength of the breeze depends on the strength of the land-sea temperature difference (gradient). Sea/lake breezes occur mid to late afternoon when the land-sea temperature difference (gradient) is greatest and tend to be more intense than land breezes. Although, thunderstorms may develop if atmospheric instability is enhanced by surface heating.

Land breezes, on the other hand, are a reverse circulations that tend to occur during the pre-dawn hours. At night, the land surface cools more rapidly than the sea thus becoming denser resulting in a higher surface pressure and an offshore flow.