Diurnal air temperature variation
In
Temperature lag
Temperature lag, also known as
As solar energy strikes the Earth's surface each morning, a shallow 1–3-centimetre (0.39–1.18 in) layer of air directly above the ground is heated by conduction. Heat exchange between this shallow layer of warm air and the cooler air above is very inefficient. On a warm summer's day, for example, air temperatures may vary by 16.5 °C (30 °F) from just above the ground to chest height. Incoming solar radiation exceeds outgoing heat energy for many hours after noon and equilibrium is usually reached from 3–5 p.m., but this may be affected by a variety of factors such as large bodies of water, soil type and cover, wind, cloud cover/water vapor, and moisture on the ground.[1]
Differences in variation
The examples and perspective in this section may not represent a worldwide view of the subject. (February 2020) |
Diurnal temperature variations are greatest very near Earth's surface. The
High desert regions typically have the greatest diurnal-temperature variations, while low-lying humid areas near the shores (tropical, oceanic, and arctic) typically have the least. This explains why an area like the
While the National Park Service claimed that the world single-day record is a variation of 102 °F (56.7 °C) (from 46 °F or 7.8 °C to −56 °F or −48.9 °C) in Browning, Montana in 1916,[2] the Montana Department of Environmental Quality claimed that Loma, Montana also had a variation of 102 °F (56.7 °C) (from −54 °F or −47.8 °C to 48 °F or 8.9 °C) in 1972.[3] Both these extreme daily temperature changes were the result of sharp air-mass changes within a single day. The 1916 event was an extreme temperature drop, resulting from frigid Arctic air from Canada invading northern Montana, displacing a much warmer air mass. The 1972 event was a chinook event, where air from the Pacific Ocean overtopped mountain ranges to the west, and dramatically warmed in its descent into Montana, displacing frigid Arctic air and causing a drastic temperature rise.
In the absence of such extreme air-mass changes, diurnal temperature variations typically range from 10 or fewer degrees in humid, tropical areas, to 40-50 degrees in higher-elevation, arid to semi-arid areas, such as parts of the U.S. Western states' Intermountain Plateau areas, for example Elko, Nevada, Ashton, Idaho and Burns, Oregon. The higher the humidity is, the lower the diurnal temperature variation is.
In
In Australia, significant diurnal temperature variations generally occur in the Red Centre around Alice Springs and Uluru.
Viticulture
Diurnal temperature variation is of particular importance in
See also
References
- ^ a b M. Hackworth "Weather & Climate" course notes, with prior permission Archived October 12, 2008, at the Wayback Machine
- ^ Weather - Glacier National Park
- ^ Montana Department of Environmental Quality (DEQ) - FAQ Archived July 28, 2013, at the Wayback Machine
- ISBN 0-19-860990-6