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14-728: The Platißbach is a roughly seven-kilometre-long (4.3 mi), southern and orographically right-hand tributary of the River Olef in the municipality of Hellenthal in Germany . The Platißbach rises in the High Fens-Eifel Nature Park in the North Eifel natural region of the Hollerath Plateau . Its source lies about 2.5 kilometres (1.6 mi) northwest of the village of Hollerath and one kilometre (0.6 mi) north of

28-602: Is a major factor for meteorologists 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 updraft speed are major contributors when it comes to achieving the optimal amount and intensity of orographic precipitation. Computer models simulating these factors have shown that narrow barriers and steeper slopes produce stronger updraft speeds, which in turn increase orographic precipitation. Orographic precipitation

42-423: Is being lifted expands and cools adiabatically. This adiabatic cooling of a rising moist air parcel may lower its temperature to its dew point , thus allowing for condensation of the water vapor contained within it, and hence the formation of a cloud . If enough water vapor condenses into cloud droplets, these droplets may become large enough to fall to the ground as precipitation. Terrain-induced precipitation

56-428: Is either warmer or less dense than itself. The converse will occur for a mass of cool air, and is known as subsidence . This movement of large volumes of air, especially when regions of hot, wet air rise, can create large clouds , and is the central source of thunderstorms . Drafts can also be caused by low or high pressure regions. A low pressure region will attract air from the surrounding area, which will move towards

70-655: Is known to occur on oceanic islands , such as the Hawaiian Islands and New Zealand ; much of the rainfall received on such islands is on the windward side, and the leeward side tends to be quite dry, almost desert -like. This phenomenon results in substantial local gradients in the amount of average rainfall, with coastal areas receiving on the order of 20 to 30 inches (510 to 760 mm) per year, and interior uplands receiving over 100 inches (2,500 mm) per year. Leeward coastal areas are especially dry—less than 20 in (510 mm) per year at Waikiki —and

84-482: Is the study of the topographic relief of mountains , and can more broadly include hills, and any part of a region's elevated terrain. Orography (also known as oreography , orology, or oreology ) falls within the broader discipline of geomorphology . The term orography comes from the Greek : όρος , hill, γράφω , to write. Mountain ranges and elevated land masses have a major impact on global climate. For instance,

98-674: The Belgian border at a height of about 605 m. The Platißbach initially flows in a northern direction. After about one kilometre (0.6 mi) it collects an unnamed stream from the left and changes direction to head east. On reaching the B 265 it changes course again and flows parallel to the road in a northwesterly direction to its mouth. On its way it flows through the Platißbach Valley Nature Reserve. The Platißbach picks up other tributaries from both sides, near Platiß  [ de ; nl ] (a district of Hellenthal),

112-572: The center and then rise, creating an updraft. A high pressure region will attract air from the surrounding area, which will move towards the center and sink, spawning a downdraft . Updrafts and downdrafts, along with wind shear in general, are a major contributor to airplane crashes during takeoff and landing in a thunderstorm. Extreme cases, known as downbursts and microbursts, can be deadly and difficult to predict or observe. The crash of Delta Air Lines Flight 191 on its final approach before landing at Dallas/Fort Worth International Airport in 1985

126-468: The elevated areas of East Africa substantially determine the strength of the Indian monsoon . In scientific models, such as general circulation models , orography defines the lower boundary of the model over land. When a river's tributaries 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

140-467: 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, also known as relief precipitation, is precipitation generated by a forced upward movement of air upon encountering a physiographic upland (see anabatic wind ). This lifting can be caused by: Upon ascent, the air that

154-734: The only village it passes, at a height of about 422 m, it is joined by its main tributary, the Prether Bach  [ de ; ce ] . In Hellenthal it empties into the Urft tributary, the Olef , at about 403 m. The catchment of the Platißbachs is 38.6 km (14.9 sq mi) in area and drains over the Olef, Urft, Rur, Meuse and Hollands Diep into the North Sea. Orographically Orography

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168-500: The tops of moderately high uplands are especially wet—about 475 in (12,100 mm) per year at Wai'ale'ale on Kaua'i . Another area in which orographic precipitation is known to occur is the Pennines in the north of England : 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

182-456: The western slopes. This is particularly noticeable between Manchester (to the west) and Leeds (to the east); Leeds receives less rain due to a rain shadow of 12 miles (19 km) from the Pennines. Updraft Vertical drafts, known as updrafts or downdrafts, are localized regions of warm or cool air that move vertically. A mass of warm air will typically be less dense than the surrounding region, and so will rise until it reaches air that

196-550: Was presumably caused by a microburst, and prompted the Federal Aviation Administration (FAA) to research and deploy new storm detection radar stations at some of the major airports, notably those in the South, Midwest, and Northeast United States where wind shear affects air safety . Downbursts can cause extensive localized damage, similar to that caused by tornadoes . Downburst damage can be differentiated from that of

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