Breezes

Breezes are light, local winds that arise from differential heating or cooling of surfaces. They typically operate over small geographic areas and are common in coastal regions and in areas with strong topographic contrasts, where thermal or pressure differences create steady, shallow air movements.

The most familiar breeze is the sea breeze. During the day, land heats up more quickly than the sea, causing the air over the land to rise and the cooler air from the sea to move toward shore. This onshore flow can bring cooler, humid air inland. At night, the situation often reverses, producing a land breeze as coastal air cools and moves toward the sea.

Thermally driven flows also occur along slopes. Valley breezes develop during the day as warm air rises up the valley walls, moving air from the valley floor toward higher terrain. Mountain or downslope breezes occur at night when cooler air descends along the slopes. These flows are typically lighter than coastal breezes but can still influence local weather and air quality.

Other contributing factors include urban heating, which can create localized breezes within cities, and katabatic or anabatic flows on steeper slopes, which are driven by gravity and temperature differences.

Typical speeds for breezes range from a few meters per second to around 10 m/s (roughly 5–22 mph), with many examples well under 5 m/s. Breezes affect comfort, outdoor activity, sailing and boating, dispersion of pollutants, and microclimates in coastal and mountainous regions. They are measured with standard anemometers and monitored by weather stations as part of local meteorological observations.