Question

It is late afternoon on a warm summer day and you are enjoying some time at the beach. Until the last hour or two, winds were calm. Then a breeze began to develop. Is it more likely a cool breeze from the water or a warm breeze from the adjacent land area? Explain.

Short answer

It is a cool sea breeze from the water.

Step-by-step solution

Understand the Context

On a warm summer day at the beach, the land heats up faster than the water due to differences in specific heat capacity.

Analyze Temperature Differences

The land, having a lower specific heat capacity, gets warmer quickly in the afternoon compared to the water, which remains relatively cooler.

Determine the Wind Direction

A breeze typically flows from a cooler area to a warmer area due to the pressure difference created by temperature gradients.

Apply Concept of Sea Breeze

In this scenario, the breeze likely flows from the cooler water towards the warmer land, known as a sea breeze.

Conclusion

Considering the factors involved, the breeze in the late afternoon is more likely to be a cool breeze coming from the water.

Key concepts

Specific Heat Capacity

Specific heat capacity is a crucial concept in understanding why the land heats up faster than the water. It refers to the amount of heat required to change the temperature of a substance by one degree.

Water has a higher specific heat capacity than land, meaning it requires more energy to increase its temperature by one degree. On the other hand, land heats up quickly because it has a lower specific heat capacity.

This is why during the day, especially in the afternoon, the land becomes significantly warmer than the adjacent water body. Consequently, understanding specific heat capacity helps explain the development of sea breezes at the beach.

• High specific heat capacity: Water
• Low specific heat capacity: Land
• Outcome: Land heats up faster than water

Temperature Gradients

Temperature gradients represent the change in temperature across a particular distance. At the beach, as the land warms up faster than the water, a temperature gradient is created between the water and the land.

In basic terms, this means there's a noticeable difference in temperature between the two areas. The land, getting heated more quickly, becomes warmer compared to the cooler water.

As the sun warms the land throughout the day, the temperature gradient becomes steeper. This gradient is an essential factor that influences the formation of breezes, as it drives the movement of air from regions of different temperatures.

• Warmer land vs. Cooler water
• Steep temperature gradient

Wind Direction

Wind direction is largely determined by the differences in temperature and resulting pressure changes in the environment. Typically, air moves from areas of higher pressure to areas of lower pressure, and this movement is what we feel as wind.

In the context of sea breezes, during the late afternoon, the air over the land is warmer and thus rises, creating a low-pressure area. The cooler air over the water, characterized by high pressure, moves towards this lower pressure area over the land.

This consistent movement of air from the cooler water towards the warmer land is referred to as the sea breeze and helps to cool down coastal areas in the afternoon by bringing in cooler air.

• High pressure to low pressure
• Cooler water to warmer land

Pressure Differences

Pressure differences are the driving force behind the formation of winds, including sea breezes. Air pressure varies with temperature, as warmer air tends to rise, creating a low-pressure zone, while cooler air is denser and remains close to the surface, creating a high-pressure zone.

At the beach, the land heated by the sun during the day results in rising warm air, creating low pressure, while over the water, the air remains cooler and at a higher pressure.

The resulting pressure difference causes air to move from the high-pressure area over the water towards the lower pressure area over the land. This movement of air helps equilibrate the pressure and temperature differences, forming what is known as a sea breeze, providing relief from the heat on land.

• Low pressure: Warmer land
• High pressure: Cooler water