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Orography is the study of the topographic relief of , and can more broadly include hills, and any part of a region's elevated terrain. Orography (). American Meteorological Society. Orography (also known as oreography, orology, or oreology) falls within the broader discipline of . The term orography comes from the : όρος, hill, γράφω, to write.


Uses
Mountain ranges and elevated land masses have a major impact on . For instance, the elevated areas of substantially determine the strength of the Indian monsoon.Srinivasan, J., Nanjundiah, Ravi S. and Chakraborty, Arindam (2005). "Impact of Orography on the Simulation of Monsoon Climate in a General Circulation Model". Indian Institute of Science. In scientific models, such as general circulation models, orography defines the lower boundary of the model over land.

When a river's or settlements by the river are listed in 'orographic sequence', they are in order from the highest (nearest the source of the river) to the lowest or mainstem (nearest the mouth). This method of listing tributaries is similar to the Strahler Stream Order, where the headwater tributaries are listed as category 1.


Orographic precipitation
Orographic precipitation, also known as relief precipitation, is precipitation generated by a forced upward movement of air upon encountering a physiographic upland (see ). This lifting can be caused by:

  1. Upward deflection of large-scale horizontal flow by the orography.
  2. Anabatic or upward vertical propagation of moist air up an orographic slope, caused by daytime heating of the mountain barrier surface.

Upon ascent, the air that is being lifted expands and cools adiabatically. This adiabatic cooling of a rising moist air parcel may lower its temperature to its , thus allowing for condensation of the water vapor contained within it, and hence the formation of a . If enough water vapor condenses into cloud droplets, these droplets may become large enough to fall to the ground as precipitation.

precipitation is a major factor for to consider when they forecast the local weather. Orography can play a major role in determining the type, amount, intensity, and duration of precipitation events. Researchers have discovered that barrier width, slope steepness, and speed are major contributors when it comes to achieving the optimal amount and intensity of orographic precipitation. simulating these factors have shown that narrow barriers and steeper slopes produce stronger updraft speeds, which in turn increase orographic precipitation.

Orographic precipitation is known to occur on oceanic , such as the and ; much of the rainfall received on such islands is on the windward side, and the side tends to be quite dry, almost -like. This phenomenon results in substantial local gradients in the amount of average rainfall, with coastal areas receiving on the order of per year, and interior uplands receiving over per year. Leeward coastal areas are especially dry—less than per year at —and the tops of moderately high uplands are especially wet—about per year at Wai'ale'ale on Kaua'i.

Another area in which orographic precipitation is known to occur is the in the north of : the west side of the Pennines receives more rain than the east because the clouds are forced up and over the hills and cause the rain to tend to fall on the western slopes. This is particularly noticeable between (to the west) and (to the east); Leeds receives less rain due to a rain shadow of from the Pennines.


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