Diurnal temperature variation

In meteorology, diurnal temperature variation is the variation between a high temperature and a low temperature that occurs during the same day.

July diurnalvariation US
Map of diurnal temperature variation for the month of July in the contiguous United States

Temperature lag

Temperature lag is an important factor in diurnal temperature variation: peak daily temperature generally occurs after noon, as air keeps net absorbing heat even after noon, and similarly minimum daily temperature generally occurs substantially after midnight, indeed occurring during early morning in the hour around dawn, since heat is lost all night long. The analogous annual phenomenon is seasonal lag.

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 waist 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 different things such as large bodies of water, soil type and cover, wind, cloud cover/water vapor, and moisture on the ground.[1]

Differences in variation

Diurnal temperature variations are greatest very near Earth's surface.

High desert regions typically have the greatest diurnal-temperature variations, while low-lying humid areas typically have the least. This explains why an area like the Snake River Plain can have high temperatures of 38 °C (100 °F) during a summer day, and then have lows of 5–10 °C (41–50 °F). At the same time, Washington D.C., which is much more humid, has temperature variations of only 8 °C (14 °F);[1] urban Hong Kong has a diurnal temperature range of little more than 4 °C (7.2 °F).

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.


Diurnal temperature variation is of particular importance in viticulture. Wine regions situated in areas of high altitude experience the most dramatic swing in temperature variation during the course of a day. In grapes, this variation has the effect of producing high acid and high sugar content as the grapes' exposure to sunlight increases the ripening qualities while the sudden drop in temperature at night preserves the balance of natural acids in the grape.[4]

See also


  1. ^ a b M. Hackworth "Weather & Climate" course notes, with prior permission Archived October 12, 2008, at the Wayback Machine
  2. ^ Weather - Glacier National Park
  3. ^ Montana Department of Environmental Quality (DEQ) - FAQ Archived July 28, 2013, at the Wayback Machine
  4. ^ J. Robinson "The Oxford Companion to Wine" Third Edition pg 691 Oxford University Press 2006 ISBN 0-19-860990-6
Anderson Valley AVA

The Anderson Valley AVA is an American Viticultural Area centered on the Anderson Valley in Mendocino County, California. It is known primarily for its Pinot noir and sparkling wine production. Lying 10 to 15 miles (16 to 24 km) from the Pacific Ocean, the AVA is prone to wide diurnal temperature variation of between 40 to 50 °F (22 to 28 °C). The valley frequently has long Indian summers. Wineries in the AVA host an annual Alsatian wine festival where locally produced Riesling and Gewurztraminer wines are showcased.

Atlas Peak AVA

The Atlas Peak AVA is an American Viticultural Area located within Napa Valley AVA just northeast of the city of Napa. The appellation sits on a higher elevation than most of Napa's wine region which limits the effects of the cool fog coming in from Pacific Ocean. The westward orientation of most vineyards on the Vaca Mountains also extends the amount of direct sunlight on the grapes. The soil of this AVA is volcanic and very porous which allows it to cool down quickly despite the increased sunlight. The area has a fairly significant diurnal temperature variation upwards of 30 °F (17 °C) between daytime and night. This contributes to the balance of acidity that grapes from Atlas Peak vineyards are known to have.

Atmosphere of Earth

The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation).

By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere. Air content and atmospheric pressure vary at different layers, and air suitable for use in photosynthesis by terrestrial plants and breathing of terrestrial animals is found only in Earth's troposphere and in artificial atmospheres.

The atmosphere has a mass of about 5.15×1018 kg, three quarters of which is within about 11 km (6.8 mi; 36,000 ft) of the surface. The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. The Kármán line, at 100 km (62 mi), or 1.57% of Earth's radius, is often used as the border between the atmosphere and outer space. Atmospheric effects become noticeable during atmospheric reentry of spacecraft at an altitude of around 120 km (75 mi). Several layers can be distinguished in the atmosphere, based on characteristics such as temperature and composition.

The study of Earth's atmosphere and its processes is called atmospheric science (aerology). Early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann.

Calistoga AVA

The Calistoga AVA is an American Viticultural Area located in the northern portion of California's Napa Valley AVA. The appellation is distinguished by its volcanic soil, high temperatures up to 100 °F (38 °C) during the day, and cool nights during the growing season due to breezes from the Russian River, causing the highest diurnal temperature variation in the Napa Valley—up to 50 °F (28 °C).

Covelo AVA

The Covelo AVA is an American Viticultural Area located in northern Mendocino County, California. Although the region only has 2 acres (1 ha) under vine, it was granted AVA status by the United States Department of the Treasury Alcohol and Tobacco Tax and Trade Bureau on February 16, 2006 based purely on the unique climate conditions of the area. The appellation is located 45 miles (72 km) north of Ukiah, California and includes the areas of Round and Williams Valleys. The area is relatively flat terrain built upon deep loam layers of soil. Unlike other areas in the California wine country, Covelo has a continental climate with the high peaks surrounding the valley shielding it from the influence of the Pacific Ocean. The growing season here is one of the shortest in Mendocino County and the area experiences one of the widest diurnal temperature variation in the region.

Diurnal cycle

A diurnal cycle is any pattern that recurs every 24 hours as a result of one full rotation of the Earth around its own axis.

In climatology, the diurnal cycle is one of the most basic forms of climate patterns. The most familiar such pattern is the diurnal temperature variation. Such a cycle may be approximately sinusoidal, or include components of a truncated sinusoid (due to the Sun's rising and setting) and thermal relaxation (Newton cooling) at night.

Diurnal cycles of environmental conditions (light or temperature) can result in similar cycles in dependent biological processes, such as photosynthesis in plants, or clinical depression in humans. Plant responses to environmental cycles may even induce indirect cycles in rhizosphere microbial activities, including nitrogen fixation.A semi-diurnal cycle refers to a pattern that occurs about every twelve hours or about twice a day. Often these can be related to lunar tides, in which case the interval is closer to 12 hours and 25 minutes.

Jumla (town)

Jumla is the centre of Chandannath Municipality in Jumla District of Karnali province of Nepal. It is located at 2514 metres (8251 feet) elevation.

Lime Kiln Valley AVA

The Lime Kiln Valley AVA is an American Viticultural Area located in the larger Cienega Valley AVA in San Benito County, California. This appellation spans 2,300 acres (931 ha) and was granted AVA status in 1982. The soil in the region is composed of foundations of limestone and dolomite with sandy, gravelly loam above. The area has a wide diurnal temperature variation of up to 50 °F (28 °C), with daytime temperatures in 85 °F (29 °C) to 95 °F (35 °C) range during the summer growing seasons. The AVA is home to old vine Mourvedre plantings.

Norte Region, Portugal

Norte (Portuguese: Região do Norte, IPA: [ʁɨʒiˈɐ̃w̃ du ˈnɔɾt(ɨ)]; "North Region") or Northern Portugal is the most populous region in Portugal, ahead of Lisboa, and the third most extensive by area. The region has 3,689,173 inhabitants according to the 2011 census, and its area is 21,278 km² (density of 173 inhabitants per square kilometre). It is one of five regions of Mainland Portugal (NUTS II subdivisions). Its main population center is the urban area of Porto, with about one million inhabitants; it includes a larger political metropolitan region with 1.8 million, and an urban-metropolitan agglomeration with 2.99 million inhabitants, including Porto and a number of urban areas in Northwestern Portugal, ranging from Braga to Aveiro. The Commission of Regional Coordination of the North (CCDR-N) is the agency that coordinates environmental policies, land-use planning, cities and the overall development of this region, supporting local governments and associations.Northern Portugal is a culturally varied region. It is a land of dense vegetation and profound historic and cultural wealth. What is now Northern Portugal was first settled by various pre-Celtic and Celtic tribes before being explored by a number of Mediterranean civilizations, including Greek settlements in its river-mouths, trade with the Carthaginians, conquest by the Romans, invasion by Germanic peoples, and attacks by the Moors and the Vikings.

Redonda Beach

Redonda Beach or Praia Redonda in Portuguese, meaning Round, is a beach on the southwestern coast of Póvoa de Varzim, Portugal, bordering the Atlantic Ocean. It is adjacent to Passeio Alegre, in Póvoa de Varzim City Center. The Avenida dos Banhos runs alongside the beach, and the Diana Bar beach library, a nightclub and Café Guarda-sol are located on the beach.

The beach has medium sand and little granitic gneiss, typical rocky outcrops on Póvoa de Varzim coastline, the largest concentration is Carvalhido outcrop, which serves as the north limit of the beach. Salgueira Beach is located to the North and the Port of Póvoa de Varzim to the south. These beaches have a specific climate, by showing low diurnal temperature variation, just 4 °C (39.2 °F). Compared with the rest of the territory, rainfall is significantly lower and solar irradiation higher. These are subject to the prevailing northern winds which arise in the summer after midday, hence mornings are significantly less windy.

Reindeer Island

Reindeer Island is an island located in the north basin of Lake Winnipeg, in the Canadian province of Manitoba, closer to the western shore of the lake. Uninhabited by people, it was named Manitoba's first ecological reserve in May 1976, and was created under The Crown Lands Act. Reindeer Island is located approximately 130 km (81 mi) southeast of the community of Grand Rapids.


Rundu is the capital of the Kavango-East Region, northern Namibia, on the border with Angola on the banks of the Kavango River about 1,000 metres (3,300 feet) above sea level. The place normally receives an annual average rainfall of 565 millimetres (22.2 in), although in the 2010/2011 rainy season 757 millimetres (29.8 in) were measured.Rundu is growing rapidly. The 2001 census counted 36,964 inhabitants; and for the 2011 census it has climbed to 63,430.

San Lucas AVA

The San Lucas AVA is an American Viticultural Area located in Monterey County, California. It is located at the southern end of Salinas Valley, shares an eastern border with the Chalone AVA, and is bordered on the west by the Santa Lucia Range foothills. The appellation has the largest diurnal temperature variation of any of California's AVAs. There is a current petition to designate the San Bernabe vineyard, located at the region's northern end, as its own AVA. The vineyard is currently the world's largest continuous vineyard.

Seasonal lag

Seasonal lag is the phenomenon whereby the date of maximum average air temperature at a geographical location on a planet is delayed until some time after the date of maximum insolation. This also applies to the minimum temperature being delayed until some time after the date of minimum insolation.

An analogous temperature lag phenomenon occurs in diurnal temperature variation, where maximum daily temperature occurs after noon (maximum insolation).

Temperature lag

Temperature lag is when change in temperature lags change in radiation (heating or cooling). Meteorological examples include:

Diurnal temperature variation – e.g., peak daily temperature typically occurs after noon

Seasonal lag – e.g., peak annual temperature typically occurs after the summer solstice

Temperature range

Temperature range may refer to:

Atmospheric temperature

An aspect of climate classification

Diurnal temperature variation

Operating temperature



Wonder Valley, California

Wonder Valley is a sparsely populated unincorporated community in the Morongo Basin of Southern California's High Desert region, straddling Amboy Road and State Route 62 in San Bernardino County, California, United States, approximately 10 miles (16 km) east of the city of Twentynine Palms.

Wuzhai County

Wuzhai (Chinese: 五寨; pinyin: Wǔzhài; literally: 'five villages') is a county of northwestern Shanxi province, China. It is under the administration of Xinzhou City.

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