Katabatic winds are nocturnal phenomena in most parts of the world (i.e. Which types of local winds happen at night Why? Is it windier in a valley?īut even on most slightly windy evenings, it’s likely that the winds in valleys are calmer than on the mountains (which tend to be much higher than other places on Earth), and also probably calmer than similar areas in the Plains. As a result of this difference in cooling ability, it doesn’t take long for the ground to become colder than the air above it. The wind speed tends to decrease after sunset because at night the surface of the Earth cools much more rapidly than does the air above the surface. This gentle upslope wind known as a valley breeze. The warmer and less dense air near the ground rises during the day pulling more air through the valley floor. Do valley breezes occur during the day?ĭuring the day, sunlight warms the land and air in the Valley and along the slopes of the mountains. It flows downhill into the valley at night. Why does air flow from mountains down into valleys? Because cold air is dense.

Why does air flow down from mountains into valleys at night? Air from the lower valley moves in to replace it, creating an upslope breeze that becomes strongest around noon. Valley Breeze- Develops during the day when the thin air above the high mountainsides warms quickly and the warm air rises and creates local low pressure along the slopes. What time of day would a valley breeze happen Why? It occurs at night, when the highlands radiate heat and are cooled.

Katabatic wind, also called downslope wind, or gravity wind, wind that blows down a slope because of gravity.

Define valley breeze