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The oasis effect refers to the creation of a local microclimate that is cooler than the surrounding dry area due to
The oasis effect plays a role in urban development because plants and bodies of water result in cooler cities. Accordingly, cities with
The oasis effect refers to the creation of a local microclimate that is cooler than the surrounding dry area due to evaporation
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...
or evapotranspiration of a water source or plant life and higher albedo of plant life than bare ground. The oasis effect is so-named because it occurs in desert
A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
oases
In ecology, an oasis (; ) is a fertile area of a desert or semi-desert environment'ksar''with its surrounding feeding source, the palm grove, within a relational and circulatory nomadic system.”
The location of oases has been of critical imp ...
. Urban planners
An urban planner (also known as town planner) is a professional who practices in the field of town planning, urban planning or city planning.
An urban planner may focus on a specific area of practice and have a title such as city planner, town ...
can design a city's layout to optimize the oasis effect to combat the urban heat island effect. Since it depends on evaporation, the oasis effect differs by season.
Causes
An oasis contains moisture from a water source and/or plants. When that water evaporates or transpirates, heat from the surroundings is used to convertliquid
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...
to gas in an endothermic process, which results in cooler local temperatures. Moreover, vegetation has a higher albedo than bare ground, and reflects more sunlight
Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when t ...
, leading to lower land temperatures, lower air temperatures, and a cooler local microclimate.
Seasonal effects
The oasis effect occurs most prominently during the summer because warmer temperatures lead to more evaporation. In the winter, the oasis effect operates differently. Instead of making the oasis cooler, the oasis effect makes it warmer at night. This occurs through the fact that trees block heat from leaving the land. Basically,radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes:
* ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...
cannot be emitted back into the atmosphere
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...
because the trees intercept and absorb it.
Urban planning
The oasis effect plays a role in urban development because plants and bodies of water result in cooler cities. Accordingly, cities with parks
A park is an area of natural, semi-natural or planted space set aside for human enjoyment and recreation or for the protection of wildlife or natural habitats. Urban parks are urban green space, green spaces set aside for recreation inside t ...
will have lower temperatures because plants have higher albedo than bare ground or roads. Areas with higher albedo reflect more light than they absorb, leading to cooler temperatures. Normally, cities are hotter than their suburbs due to dense population, dark buildings and roads, and pollution; this is known as the urban heat island effect. However, by careful placement of trees, parks, and plant life, cities can create their own oasis effect. By maintaining plant life throughout a city, urban planners can produce an oasis effect to offer the urban heat island effect; even a small scattering of trees can significantly reduce local temperatures. However, concerns can arise in arid regions with limited water sources where city planners may not want to leave water sources out in the open to evaporate, and may not want to sacrifice water for upkeep of plants.
See also
*Urban climate The climate in urban areas differs from that in neighboring rural areas, as a result of urban development. Urbanization greatly changes the form of the landscape, and also produces changes in an area's air. The study of urban climate is urban climat ...
*Water-sensitive urban design
Water-sensitive urban design (WSUD) is a land planning and engineering design approach which integrates the urban water cycle, including stormwater, groundwater, and wastewater management and water supply, into urban design to minimise environme ...
* Green roof
*Oasis
In ecology, an oasis (; ) is a fertile area of a desert or semi-desert environment'ksar''with its surrounding feeding source, the palm grove, within a relational and circulatory nomadic system.”
The location of oases has been of critical imp ...
* Evaporative Cooling
References
{{reflist Climate patterns Hydrogeology Hydrology Meteorological concepts