Winds Summary Wind is the horizontal movement of air from an area of high pressure to an area of low pressure. Wind is caused by pressure differences. Local Winds are caused by the unequal heating of Earth’s surface within a small area. Sea Breeze happens during the day because the land heats up faster than the water. The water is cooler, making the air above it cooler (more dense). This creates higher pressure above the water. The land is warmer during the day making the air above the land warmer and less dense. The air rises, creating an area of low pressure over the land. The cooler more dense, higher pressure air moves toward the warmer, lower density, lower pressure air over the land. Land breeze happens at night because the land cools faster than the water. Air over the land is cooler (more dense) and creates an area of high pressure. Air over the water is warmer (less dense) and creates an area of low pressure. The cooler more dense, higher pressure air moves toward the warmer less dense, lower pressure air over the water. Air moves from high to low pressure.