AirTemperature.pptVIP

Air Temperature Chapter 3 Overview Daily Temperature Variations Daytime Warming, Nighttime cooling Cold Air near the surface The Controls of Temperature Air Temperature data Daily, Monthly, and Yearly Temps The use of temp data Measuring air temp Daily Temperature Variations Air temperature is a very important weather element. Impacts us every day. If it is warm we don’t always mind the rain, but if its cold…..Or if it is 100°F outside… A sunny day has its own cycle of warming and cooling. Temperature lag – Sun directly overhead at noon, but noon is not warmest point of a sunny day. Why? Nighttime Cooling As sun lowers, its energy is spread over a larger area, which reduces the heat available to warm the ground. Sometime in the late afternoon or early evening, the earth’s surface and air above begin to lose more energy than they receive, they start to cool. Radiational Cooling – ground and air above cool by radiating infrared energy. The ground, being a much better radiator than air, is able to cool more quickly. Shortly after sunset the earth’s surface is slightly cooler than the air directly above it. By late night or early morning the coldest air is next to the ground with slightly warmer air above. Radiation Inversion Strong radiation inversion occurs when the air near the ground is much colder than the air higher up. Ideal conditions: Calm conditions – no mixing Long nights – more time for radiational cooling Dry air, cloud-free – clear skies allow maximum cooling at the surface Freeze A coating of ice protects these almond trees from damaging low temperatures, as an early spring freeze drops air temperatures well below freezing. A freeze occurs over a widespread area when the surface air temperature remains below freezing for a long enough time to damage certain agricultural crops Controls of Temperature Latitude (colder near the poles, warmer near equator) Land and water distribution (i.e. Great lakes - water cools surrounding land masses in