HOME

TheInfoList



OR:

A microclimate (or micro-climate) is a local set of atmospheric conditions that differ from those in the surrounding areas, often with a slight difference but sometimes with a substantial one. The term may refer to areas as small as a few square meters or square feet (for example a garden bed or a cave) or as large as many square kilometers or square miles. Because
climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...
is statistical, which implies spatial and temporal variation of the mean values of the describing
parameter A parameter (), generally, is any characteristic that can help in defining or classifying a particular system (meaning an event, project, object, situation, etc.). That is, a parameter is an element of a system that is useful, or critical, when ...
s, within a region there can occur and persist over time sets of statistically distinct conditions, that is, microclimates. Microclimates can be found in most places but are most pronounced in topographically dynamic zones such as mountainous areas, islands, coastal areas. Microclimates exist, for example, near bodies of water which may cool the local atmosphere, or in heavy urban areas where brick, concrete, and
asphalt Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term ...
absorb the sun's energy, heat up, and re-radiate that heat to the ambient air: the resulting urban heat island (UHI) is a kind of microclimate that is additionally driven by relative paucity of
vegetation Vegetation is an assemblage of plant species and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic charac ...
.


Background

The terminology "micro-climate" first appeared in the 1950s in publications such as ''Climates in Miniature: A Study of Micro-Climate Environment'' (Thomas Bedford Franklin, 1955).


Examples of microclimates

The area in a developed industrial park may vary greatly from a wooded park nearby, as natural flora in parks absorb light and heat in leaves that a building roof or parking lot just radiates back into the air. Advocates of solar energy argue that widespread use of solar collection can mitigate overheating of urban environments by absorbing sunlight and putting it to work instead of heating the foreign surface objects. A microclimate can offer an opportunity as a small
growing region A growing region is an area suited by climate and soil conditions to the cultivation of a certain type of crop or plant group. Most crops are cultivated not in one place only, but in several distinct regions in diverse parts of the world. Cult ...
for crops that cannot thrive in the broader area; this concept is often used in
permaculture Permaculture is an approach to land management and settlement design that adopts arrangements observed in flourishing natural ecosystems. It includes a set of design principles derived using whole-systems thinking. It applies these principl ...
practiced in northern temperate climates. Microclimates can be used to the advantage of gardeners who carefully choose and position their plants. Cities often raise the average temperature by zoning, and a sheltered position can reduce the severity of winter.
Roof garden A roof garden is a garden on the roof of a building. Besides the decorative benefit, roof plantings may provide food, temperature control, hydrological benefits, architectural enhancement, habitats or corridors for wildlife, recreational op ...
ing, however, exposes plants to more extreme temperatures in both summer and winter. In an urban area, tall buildings create their own microclimate, both by overshadowing large areas and by channeling strong winds to ground level. Wind effects around tall buildings are assessed as part of a microclimate study. Microclimates can also refer to purpose-made environments, such as those in a room or other enclosure. Microclimates are commonly created and carefully maintained in museum display and storage environments. This can be done using passive methods, such as silica gel, or with active microclimate control devices. Usually, if the inland areas have a
humid continental climate A humid continental climate is a climatic region defined by Russo-German climatologist Wladimir Köppen in 1900, typified by four distinct seasons and large seasonal temperature differences, with warm to hot (and often humid) summers and freez ...
, the coastal areas stay much milder during winter months, in contrast to the hotter summers. This is the case further north on the American west coast, such as in
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...
, Canada, where
Vancouver Vancouver ( ) is a major city in western Canada, located in the Lower Mainland region of British Columbia. As the most populous city in the province, the 2021 Canadian census recorded 662,248 people in the city, up from 631,486 in 2016. ...
has an oceanic wet winter with rare frosts, but inland areas that average several degrees warmer in summer have cold and snowy winters.


Sources and influences on microclimate

Two main parameters to define a microclimate within a certain area are temperature and
humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...
. A source of a drop in temperature and/or humidity can be attributed to different sources or influences. Often a microclimate is shaped by a conglomerate of different influences and is a subject of microscale meteorology.


Cold air pool

Examples of the cold air pool (CAP) effect are Gstettneralm Sinkhole in Austria (lowest recorded temperature ) and Peter Sinks in the US. The main criterion on the wind speed v in order to create a warm air flow penetration into a CAP is the following: : \mathrm = \frac \geq \mathrm_c, where \mathrm is the Froude number, N — the Brunt–Väisälä frequency, h — depth of the valley, and \mathrm_c — Froude number at the threshold wind speed.


Craters

The presence of permafrost close to the surface in a crater creates a unique microclimate environment.


Caves

Caves are important geologic formations that can house unique and delicate geologic/biological environments. The vast majority of caves found are made of calcium carbonates such as limestone(see Cave and
Limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...
). In these dissolution environments, many species of flora and fauna find home. The mixture of water content within the cave atmosphere, air pressure, geochemistry of the cave rock as well as the waste product from these species can combine to make unique microclimates within cave systems. The speleogenetic effect is an observed and studied process of air circulation within cave environments brought on by convection. In phreatic conditions the cave surfaces are exposed to the enclosed air(as opposed to submerged and interacting with water from the water table in vadose conditions). This air circulates water particles that condense on cave walls and formations such as speleothems. This condensing water has been found to contribute to cave wall erosion and the formation of morphological features. Some examples of this can be found in the limestone walls of Grotta Giusti; a thermal cave near Monsummano, Lucca, Italy. Any process that leads to an increase or decrease in chemical/physical processes will subsequently impact the environment within that system. Air density within caves, which directly relates to the convection processes, is determined by the air temperature, humidity, and pressure. In enclosed cave environments, the introduction of bacteria, algae, plants, animals, or human interference can change any one of these factors therefore altering the microenvironment within the cave. There are over 750 caves worldwide that are available for people to visit. The constant human traffic through these cave environments can have a negative effect on the microclimates as well as on the geological and archeological findings. Factors that play into the deterioration of these environments include nearby deforestation, agriculture operations, water exploitation, mining, and tourist operations. The speleogenetic effect of normal caves tends to show a slow circulation of air. In unique conditions where acids are present, the effects of erosion and changes to the microenvironment can be drastically enhanced. One example is the effect of the presence of hydrosulfuric acid(H2S). When the oxidized hydrosulfuric acid chemically alters to sulfuric acid(H2SO4), this acid starts to react with the calcium carbonate rock at much higher rates. The water involved in this reaction tends to have a high pH of 3 which renders the water almost unlivable for many bacteria and algae. An example of this can be found in the Grotta Grande del Vento cave in Ancona, Italy.


Plant microclimate

As pointed out by Rudolf Geiger in his book not only climate influences the living plant but the opposite effect of the interaction of plants on their environment can also take place, and is known as ''plant climate''. This effect has important consequences for forests in the midst of a continent; indeed, if forests were not creating their own clouds and
water cycle The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle that describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly co ...
with their efficient evapotranspiration activity, there would be no forest far away from coasts, as statistically, without any other influence, rainfall occurrence would decrease from the coast towards inland. Planting trees to fight drought has also been proposed in the context of afforestation.


Dams

Artificial reservoirs as well as natural ones create microclimates and often influence the macroscopic climate as well.


Slopes

Another contributing factor of microclimate is the slope or aspect of an area. South-facing slopes in the Northern Hemisphere and north-facing slopes in the Southern Hemisphere are exposed to more direct sunlight than opposite slopes and are therefore warmer for longer periods of time, giving the slope a warmer microclimate than the areas around the slope. The lowest area of a glen may sometimes frost sooner or harder than a nearby spot uphill, because cold air sinks, a drying breeze may not reach the lowest bottom, and humidity lingers and precipitates, then freezes.


Soil types

The type of soil found in an area can also affect microclimates. For example, soils heavy in clay can act like pavement, moderating the near ground temperature. On the other hand, if soil has many air pockets, then the heat could be trapped underneath the topsoil, resulting in the increased possibility of frost at ground level.


Cities and regions known for microclimates


Americas

* Northern California above the Bay Area is also well known for microclimates with significant differences of temperatures. The coastline typically averages between during summer months along that coastline, but inland towns not far from the ocean such as Lakeport, average as much as in spite of being just around inland. Even as far north as the
Klamath River The Klamath River ( Karuk: ''Ishkêesh'', Klamath: ''Koke'', Yurok: ''Hehlkeek 'We-Roy'') flows through Oregon and northern California in the United States, emptying into the Pacific Ocean. By average discharge, the Klamath is the second la ...
valley around the 41st parallel north between Willow Creek and Eureka averages such temperatures, which is extremely hot for such northerly areas. At this parallel, the temperature at the coast is so cool that Willow Creek beats Eureka's all-time record temperature on average 79 times per year. This is in spite of the areas being less than from each other. In oceanic stable terms it is like traveling from the summers in the north of
England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...
to the south of
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = '' Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , ...
in a fraction of the distance. **
San Francisco San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17t ...
is a city with microclimates and sub microclimates. Due to the city's varied topography and influence from the prevailing summer marine layer, weather conditions can vary by as much as 9 °F (5 °C) from block to block. The
Noe Valley Noe Valley ( ; originally spelt Noé) is a neighborhood in the central part of San Francisco, California. It is named for Don José de Jesús Noé, noted 19th-century Californio statesman and ranchero, who owned much of the area and served as ma ...
district for example, is typically warmer and sunnier than adjacent areas because the surrounding hills block some of the cool fog from the Pacific. ** The region as a whole, known as the
San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area G ...
can have a wide range of extremes in temperature. In the basins and valleys adjoining the coast, climate is subject to wide variations within short distances as a result of the influence of topography on the circulation of marine air. The San Francisco Bay Area offers many varieties of climate within a few miles. In the Bay Area, for example, the average maximum temperature in July is about at Half Moon Bay on the coast, at Walnut Creek only inland, and at Tracy, just inland. * The
Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world ...
and
San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States ...
areas are also subject to phenomena typical of a microclimate. The temperatures can vary as much as ) between inland areas and the coast, with a temperature gradient of over one degree per mile (1.6 km) from the coast inland. Hills and mountains can also block coastal air masses. The San Fernando Valley is usually much warmer in summer than most of Los Angeles, because the Santa Monica Mountains usually block the cool ocean breezes and fog. Southern California has also a weather phenomenon called " June Gloom" or "May Grey", which sometimes gives overcast or foggy skies in the morning at the coast, but usually gives sunny skies by noon, during late spring and early summer. * The
Big Island of Hawaii Hawaii ( ; haw, Hawaii ) is the largest island in the United States, located in the state of Hawaii. It is the southeasternmost of the Hawaiian Islands, a chain of volcanic islands in the North Pacific Ocean. With an area of , it has 63% of t ...
is also an area known for microclimates, as Kailua-Kona and Hilo, Hawaii, experience rainfall of and per year, respectively, despite being just from each other. * Calgary, Alberta, is also known for its microclimates. Especially notable are the differences between the downtown and river valley/flood plain regions and the areas to the west and north. This is largely due to an elevation difference within the city's boundaries of over , but can also be attributed somewhat, to the effects of the seasonal Chinooks. *
Halifax, Nova Scotia Halifax is the capital and largest municipality of the Canadian province of Nova Scotia, and the largest municipality in Atlantic Canada. As of the 2021 Census, the municipal population was 439,819, with 348,634 people in its urban area. Th ...
, also has numerous microclimates. Coastal temperatures and weather conditions can differ considerably from areas located just inland. This is true in all seasons. Varying elevations are common throughout the city, and it is even possible to experience several microclimates while traveling on a single highway due to these changing elevations. *
Vancouver Vancouver ( ) is a major city in western Canada, located in the Lower Mainland region of British Columbia. As the most populous city in the province, the 2021 Canadian census recorded 662,248 people in the city, up from 631,486 in 2016. ...
and its metro area also has many microclimates. North Vancouver and other regions situated on the mountain slopes get over of precipitation a year on average, while other regions to the south get around , although they are less than away. Temperatures in the Fraser Valley inland may be up to 10 °C (18 °F) warmer than the coast, while in winter they are several degrees colder. * Chesapeake Bay is also known for its subtropical microclimate. It is most notable for its mild climatic effects on the area east and west of the lowlands of Maryland and Delmarva. Having over of water; (most of which is a mix of fresh and salt water) creates higher levels of humidity and heat in the spring and summer months. An example of this effect is the survival of tropical palm trees and plants such as water hyacinths in the area. *
Chile Chico Chile Chico (Spanish for ''Little Chile'') is a town in General Carrera Province, Aisén Region, Patagonia, Chile. It is located on the south shore of General Carrera Lake. Chile Chico, which has around 3,000 inhabitants, is the eponymous c ...
and Los Antiguos on the southern shores of General Carrera Lake have favourable conditions for
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
despite being in inner Patagonia. *
New York City New York, often called New York City or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...
and its surrounding metro area feature a mega urban heat island, and influence from the Atlantic ocean. These factors cause it to be the northernmost major city with a subtropical climate, with the city being in the 7a/7b/8a usda zones, compared to nearby cities south of it, which feature lower zones.


Europe

* Known for its wines, the
Ticino Ticino (), sometimes Tessin (), officially the Republic and Canton of Ticino or less formally the Canton of Ticino,, informally ''Canton Ticino'' ; lmo, Canton Tesin ; german: Kanton Tessin ; french: Canton du Tessin ; rm, Chantun dal Tessin . ...
region in
Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...
benefits from a microclimate in which palm trees and banana trees grow. * Gran Canaria is called "Miniature Continent" for its rich variety of microclimates. * Tenerife is known for its wide variety of microclimates. *
Biddulph Grange Biddulph Grange is a National Trust landscaped garden, in Biddulph near Stoke-on-Trent, Staffordshire, England. It is separate from Biddulph Grange Country Park. Description "Behind a gloomy Victorian shrubbery there's a gloomy Victorian mans ...
is very rich with microclimates as a result of the large dips and variety of very large trees alongside a large amount of water. *
Leeds Leeds () is a city and the administrative centre of the City of Leeds district in West Yorkshire, England. It is built around the River Aire and is in the eastern foothills of the Pennines. It is also the third-largest settlement (by popul ...
, located in Yorkshire, England, is known to have a number of microclimates because of the number of valleys surrounding the city centre. * The central west coast of Portugal, similarly to California, has huge differences in summer temperatures from the surrounding inland regions. In less than , average daily summer temperatures can vary through as much as , from in Peniche or São Pedro de Moel to around in Santarém or Tomar. This phenomenon is caused by local upwelling created by the northern Nortada winds. * The coastal areas in the Andalusia region of
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = '' Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , ...
has a microclimate. It typically averages around at in summer, but Tarifa only averages . Further north along the coast
Cádiz Cádiz (, , ) is a city and port in southwestern Spain. It is the capital of the Province of Cádiz, one of eight that make up the autonomous community of Andalusia. Cádiz, one of the oldest continuously inhabited cities in Western Europe, ...
has a summer average of with warm nights, whereas nearby Jerez de la Frontera has summer highs of with inland areas further north such as
Seville Seville (; es, Sevilla, ) is the capital and largest city of the Spanish autonomous community of Andalusia and the province of Seville. It is situated on the lower reaches of the River Guadalquivir, in the southwest of the Iberian Penins ...
being even hotter. * Sorana, a commune in Italy's Pescia Valley with a microclimate considered ideal for growing the Sorana bean.


Asia and Oceania

*
Istanbul ) , postal_code_type = Postal code , postal_code = 34000 to 34990 , area_code = +90 212 (European side) +90 216 (Asian side) , registration_plate = 34 , blank_name_sec2 = GeoTLD , blank_i ...
exhibits a multitude of distinct microclimates because of its hilly topography and maritime influences. Within the city, rainfall varies widely owing to the rain shadow of the hills in Istanbul, from around on the southern fringe at Florya to on the northern fringe at Bahçeköy. Furthermore, while the city itself lies in
USDA hardiness zones A hardiness zone is a geographic area defined as having a certain average annual minimum temperature, a factor relevant to the survival of many plants. In some systems other statistics are included in the calculations. The original and most wide ...
9a to 9b, its inland suburbs lie in zone 8b with isolated pockets of zone 8a, restricting the cultivation of cold-hardy subtropical plants to the coasts. * Amman, Jordan, has extreme examples of microclimate, and almost every neighbourhood exhibits its own weather. It is known among locals that some boroughs such as the northern and western suburbs are among the coldest in the city, and can be experiencing frost or snow whilst other warmer districts such as the city centre can be at much warmer temperatures at the same time. * Yazd and Kashan in
Iran Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
, the traditional architecture benefits from central courtyards with trees and water pools that function together with wind catchers to create a favorable microclimate in this desert area. *
Sydney Sydney ( ) is the capital city of the state of New South Wales, and the most populous city in both Australia and Oceania. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about towards the Blue Mounta ...
, Australia, has a microclimate occurring prominently in the warmer months. Inland, in Sydney's western suburbs, the climate is drier and significantly hotter with temperatures generally around above
Sydney CBD The Sydney central business district (CBD) is the historical and main commercial centre of Sydney. The CBD is Sydney's city centre, or Sydney City, and the two terms are used interchangeably. Colloquially, the CBD or city centre is often refer ...
and Eastern Suburbs (the coast), as
sea breeze A sea breeze or onshore breeze is any wind that blows from a large body of water toward or onto a landmass; it develops due to differences in air pressure created by the differing heat capacities of water and dry land. As such, sea breezes a ...
s do not penetrate further inland. In summer, the coast averages at , while inland varies between , depending on the suburb. In extreme occasions, the Coast would have a temperature of , while a suburb ) inland bakes in heat. However, winter lows in the West are around cooler than the coastal suburbs, and may provide mild to moderate frost. Within the city and surrounds, rainfall varies, from around in the far-west to at Observatory Hill (the east or the coast).


See also

* Climate categories in viticulture * Cities for Climate Protection program * Mesonet and micronet * Regional climate levels in viticulture * Terroir


References


External links


Trends in Microclimate Control of Museum Display Cases
{{Authority control Agronomy Regional climate effects