Katabatic definition of katabatic by merriamwebster. Katabatic winds exist in many parts of the world and there are many different names for katabatic winds depending where they are located and how they are formed. Katabatic, anabatic winds and their impacts in co2 c. Katabatic is a local wind caused often at night by the flow of air, cooled by radiation, down mountain slopes and valleys. Local winds occur on a small spatial scale, their horizontal. Anabatic wind a localscale wind which blows upslope, after strong heating of the hillmountainside by the sun. Paper open access characteristic of anabatic wind in. Pdf the effect of blowing snow on katabatic winds in.
The mechanism of the anabatic wind can be described as follows. Looking at the katabatic winds offers an opportunity to explore air pressure and the properties of hot and cold air. During the day, the sun heats such a slope and the air over it faster than it does the adjacent atmosphere over a valley or a plain at the same altitude. The cold air then flows down the side of the mountain, resulting in a katabatic flow or wind. It occurs at night, when the highlands radiate heat and are cooled. When air comes in contact with the warm ground surface, the air heats up, becomes less dense, and rises upward. This type of wind usually occurs on a clear sunny day. At local scales anabatic winds are an alongslope component of mountainvalley wind systems. An anabatic wind is also known as upslope wind as it is a warm wind that blows up a mountain slope due to a warmer temperature on the mountain slope compared to the temperature in the air column. Anabatic wind flowing up an incline, such as up a hillside. Those huge frozen plateaus the last remnants of the enormous ice bodies of the pleistocene glaciations reliably generate katabatic air movements along their margins.
Anabatic wind article about anabatic wind by the free. When a katabatic wind is warmed by compression during its descent into denser air, it is called a foehn. Introduction slope winds flows are typical for vast areas of the earth, and often play an important role in the weather and climate of these areas. The katabatic winds on the continent exist due to the airflow from the high pressure, cold, elevated plains down slope to the relatively warmer lower elevations with less pressure. Anabatic, adiabatic and katabatic winds sujeet singh. The effect of blowing snow on katabatic winds in antarctica article pdf available in annals of glaciology 6 january 1985 with 78 reads how we measure reads.
The flow may be as strong as 100 knots, and generally more pronounced in intensity to its opposite, anabatic wind. Due to its limited heat capacity, the surface heats the air immediately above it by conduction. What causes surface winds, mountain winds and anabatic. The air moving up the slope is subject to expansion.
In this lesson we look at valley climates and consider. Anabatic definition of anabatic by the free dictionary. A katabatic wind, from the greek word katabatikos meaning going downhill, is the technical name for a drainage wind, a wind that carries high density air from a higher elevation down a slope under the force of gravity. This air then flows up the slope, as it is at a higher temperature than the air q further away at the same level. Katabatic winds are downslope winds created when the mountain surface is colder than the surrounding air and creates a down slope wind. Katabatic winds can rush down elevated slopes at hurricane speeds, but most are not as intense as that, and many are 10 knots or less. Pdf katabatic and anabatic slope winds analysis using. Katabatic wind may range over fairly large areas as in the case of the santa anna. The northerly winds to the east of the lows tend to suppress the southerly katabatic flow, while the katabatics are enhanced by the southerly flow to the west of the depressions. Pdf evening transition between anabatic and katabatic wind flow. It is caused by ground surface cooling as a result of radiation, which in turn cools the lower air layers. Conversely, katabatic winds are downslope winds, frequently produced at night by the. Slopes occur on many scales, and consequently anabatic flows also occur on many scales.
For instance, winds such as the fohn and chinook are rain shadow. From the standpoint of basic fluid dynamics, the slope winds are buoyantly driven boundary. These winds typically occur during the daytime in calm sunny weather. This warming decreases the density of the air, causing. Katabatic definition is relating to or being a wind produced by the flow of cold dense air down a slope as of a mountain or glacier in an area subject to radiational cooling. Katabatic and anabatic winds are part of larger circulations in the valley. Anabatic wind, also called upslope wind, local air current that blows up a hill or mountain slope facing the sun. Anabatic winds are upslope winds driven by warmer surface temperatures on a mountain slope than the surrounding air column.
As the katabatic winds descend from the plateau, they interact with the synopticscale weather systems within the circumpolar trough. Therefore, in this span of time, the circulation turned into a katabatic wind regime again. Katabatic winds are most significant in the two parts of the world with grand continental ice sheets. An anabatic wind, from the greek anabatos, verbal of anabainein meaning moving upward, is a warm wind which blows up a steep slope or mountain side, driven by heating of the slope through insolation. Depending on the relative position of the sun and the angle of the orographic surface to the sun, the sunny side of valleys are more prone to anabatic winds than the shady side, where relatively colder air may even flow downwards along the orographic slope, resulting in a katabatic wind. The land area that has basin shape will have a local circulation in the form of anabatic and katabatic wind 2. Anabatic winds are especially common during the daytime in fair weather conditions. Relating to warm, rising wind currents, especially those that are driven up the slopes of hills, mountains, and peaks. Late wednesday afternoon we had a sudden literally within minutes turn around in the weather, when the winds reversed direction, a white wall of blowing snow descended on camp and the wind speed jumped high enough to make you lean into it.
What causes surface winds, mountain winds and anabatic winds. Pdf katabatic and anabatic slope winds analysis using surface. Such upslope winds can sometimes drag fog stratus in the valley bottom formed after a cold night to upland areas that were previously clear of these phenomena. As the air warms, its volume increases, and hence density and pressure decreases. Structure of numerically simulated katabatic and anabatic. Conversely, katabatic winds are downslope winds, frequently produced at. Angular momentum the energy of motion of a spinning body or mass of air or water anabatic wind a localscale wind which blows upslope, after strong heating of the hillmountainside by the sun. Anabatic article about anabatic by the free dictionary. Katabatic wind, also called downslope wind, or gravity wind, wind that blows down a slope because of gravity.
A largescale katabatic wind that descends too rapidly to warm up is called a fall wind. Anabatic definition, pertaining to an uphill wind produced by the effects of local heating. Goddard, phd and others published katabatic and anabatic slope winds analysis using surface. It is also caused by the flow of cold air down the slopes of ice caps, such as antarctica and greenland. Katabatic and anabatic winds and their impacts in co2. Anabatic wind, local air current that blows up a hill or mountain slope facing the sun. Greek katabatikos, pertaining to descent, from katabatos, descending. The fohn cumulus clouds anabatic winds this wind is again caused by thermal heat processes. Katabatic winds can be deep and powerful, so pilots usually give those southfacing slopes a respectful margin. A local wind that flows up the side of the valleys resulting from increased heating. Of or relating to the downward flow of cold dense air. As different as anabatic and katabatic helicopters.
Their field measurements focused on upslope anabatic flows. A boundarylayer scaling for turbulent katabatic flow. A katabatic wind is the technical name for a drainage wind, a wind that carries highdensity air from a higher elevation down a slope under the force of gravity. Anemometer an instrument used to measure wind speed. An anabatic wind, from the greek anabatos, verbal of anabainein meaning moving upward, is a. Anabatic upslope winds occur over slopes which are heated by the sun. Goddard, phd and others published katabatic and anabatic slope winds analysis using surface temperature equilibrium energy balance modeling micrometeorological.
At night, the katabatic winds from the bottom of the slopes drain into the. Anabatic winds are mainly created by ultraviolet solar radiation heating. In areas where fall winds occur, homes and orchards are situated on hillslopes above the lowlands where the cold air accumulates. Such upslope winds can sometimes drag fogstratus in the valley. Katabatic winds are blowing on the ground and off the high ridges. Anabatic winds can be detrimental to the maximum downhill speed of cyclists. Anabatic winds are mainly created by ultraviolet solar radiation heating up the lower regions of an orographic area i. Katabatic definition of katabatic by the free dictionary.
360 115 1603 1095 1655 895 315 1675 639 1381 517 1604 982 100 1033 607 1573 671 639 952 1341 667 430 87 606 448 1679 934 244 1010 1071 555 415 1081