In coastal towns, breezes tend to blow offshore (from the land to the ocean) during the night and early morning, and onshore (from the ocean to the land) during the afternoon and evening. What factors primarily contribute to this effect? It can be more than one answer!
Heat conduction
Heat convection
Specific heat of land vs water
Salinity of the water
Thermal expansion
The factors that primarily contribute to the breeze pattern in coastal towns are heat convection, specific heat of land vs water, and thermal expansion. Here's an explanation of each factor:
1. Heat convection: During the day, the sun heats up the land faster than the water. Land has a lower specific heat capacity, which means it requires less energy to raise its temperature compared to water. As the land heats up, the air above it also gets warmer, and warm air tends to rise. This causes the cooler air from the ocean to flow towards the land to replace the rising warm air, resulting in an onshore breeze during the afternoon and evening.
2. Specific heat of land vs water: Water has a higher specific heat capacity than land, meaning it can absorb and retain more heat energy without its temperature changing significantly. As a result, coastal waters warm up more slowly compared to the land during the day. At night, when the land cools down faster than the water, the warmer air over the water rises, and cooler air from the land flows seaward, creating an offshore breeze during the night and early morning.
3. Thermal expansion: When water is heated, it expands, causing its density to decrease. This decrease in density results in the warmer water being less dense than the surrounding cooler water. The warmer, less dense water near the coastal region then rises, and the cooler, denser water from offshore moves in to take its place, creating an onshore breeze.
Factors such as heat conduction (transfer of heat through a solid) and salinity of the water do play a role in coastal breezes but are not the primary contributors to the observed breeze patterns.