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front,

in meteorology, zone of transition between adjacent air massesair mass,
large body of air within the earth's atmosphere in which temperature and humidity, although varying at different heights, remain similar throughout the body at any one height.
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. If a cold air mass is advancing to replace a warmer one, their mutual boundary is termed a cold front; if the reverse, then the boundary is termed a warm front, whereas a stationary front indicates that no relative advance of either air mass is occurring. An occluded front is one in which a warm front has been completely undermined by cold air and is therefore positioned aloft. Since warmer air always overrides colder, denser air, the frontal boundary is sloped closer to the horizontal than the vertical. A mature cyclonecyclone,
atmospheric pressure distribution in which there is a low central pressure relative to the surrounding pressure. The resulting pressure gradient, combined with the Coriolis effect, causes air to circulate about the core of lowest pressure in a counterclockwise direction
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 usually involves all of the frontal types. The recognition of atmospheric fronts and their relative importance to weather forecasting came about only at the beginning of the 20th cent. as a result of publications by the meteorologists Vilhelm and Jakob BjerknesBjerknes, Vilhelm Frimann Koren
, 1862–1951, Norwegian physicist and pioneer in modern meteorology. He worked on applying hydrodynamic and thermodynamic theories to atmospheric and hydrospheric conditions in order to predict future weather conditions.
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.

Front

 

the transition zone between two air masses in the troposphere. A front is very narrow compared to the air masses it separates, and consequently for purposes of theoretical investigation it is considered to approximate the boundary surface between two air masses of different temperature and is called a frontal surface. For the same reason, synoptic maps depict fronts as lines.

If air masses were immobile, the surface of a front would be horizontal, with the cold air beneath and the warm air above. But because both masses are moving, the surface is inclined with respect to the earth’s surface, with the cold air forming a gently sloping wedge beneath the warm air. The tangent of the angle of inclination of the frontal surface (slope of the front) is on the order of 0.01. Fronts sometimes extend all the way to the tropo-pause, but they may also be restricted to the lower few kilometers of the troposphere. At its contact with the earth’s surface, the front is a few dozen kilometers wide, while the horizontal dimensions of the air masses themselves are on the order of thousands of kilometers. When fronts are just beginning to form or when they are dissipating, their width is greater. Vertically, fronts represent a transition layer hundreds of meters thick, in which the temperature at higher altitudes does not decrease as much as usual (the vertical temperature gradient is diminished) or it rises, that is, a temperature inversion is observed.

At the earth’s surface, fronts are characterized by larger horizontal temperature gradients—in a narrow front the temperature changes abruptly from the values characteristic of one air mass to values typical of the other, a change of sometimes more than 10°C. The air humidity and the transparency of the atmosphere also change along the front. In the barometric field, fronts are associated with troughs of low pressure, and consequently their passage causes corresponding changes in atmospheric pressure and winds. Vast cloud systems form above the frontal surfaces, including nimbostratus and cumulonimbus clouds, which produce precipitation. Fronts move at speeds equal to the normal wind velocity associated with each front. Therefore, the passage of an atmospheric front through a particular area causes a rapid change (a matter of hours) or sometimes an abrupt change in important meteorological elements, as well as a change in the weather itself.

Fronts are typical of the extratropical latitudes of the earth, in particular the temperate latitudes, where the primary air masses of the troposphere border one another. They occur rarely in the tropics; the permanent zone of intertropical convergence there differs significantly from fronts, since it is not a temperature boundary. The primary cause of the formation of fronts, called frontogenesis, is the existence of systems of movement in the troposphere, which lead to the convergence of air masses of contrasting temperatures. In the process, the originally broad transition zone between the air masses becomes relatively narrow. In certain cases, it is possible for fronts to form when air passes along an abrupt temperature boundary on an underlying surface, as, for example, over the edge of the ice in the ocean. This is known as topographic frontogenesis. In the atmospheric general circulation, there arise between the air masses of different latitudinal zones with fairly large contrasting temperatures long (thousands of kilometers), primarily latitudinal, main fronts—the arctic, antarctic, and polar fronts—where the formation of cyclones and anticyclones occurs. In this case, the dynamic stability of the main front is disrupted; the front changes and moves toward the higher latitudes in some sectors and toward the lower latitudes in others. On both sides of the frontal surface vertical wind components on the order of centimeters per second occur. The ascending movement of air above the frontal surface, which leads to the formation of cloud systems and to precipitation, is especially important.

In the forward part of a cyclone, the main front acquires the features of a warm front: as it moves toward higher latitudes, the warm air replaces the retreating cold air. In this case, the ascending movement of warm air over the very gently inclined frontal surface leads to the formation of a cloud system several hundred kilometers wide before the frontal line. In this system, the clouds change from thin, high cirrus clouds in the forward part to thick nimbostratus clouds, with steady rainfall directly ahead of the frontal line. In the rear part of a cyclone, the front has the characteristics of a cold front, in which cold air pushes forward in the form of a wedge, forcing the warm air in front of it to rise. The cloud system in a cold front is not as broad as that in a warm front, but it is characterized by a prevalence, or, in any case, the presence of cumulonimbus clouds, which produce heavy rainfall. Squalls and thunderstorms often precede the advance of the front. When a cyclone becomes occluded, the warm and cold fronts come into contact, forming a complex occluded front with corresponding changes in the cloud systems. As a result of the development of frontal disturbances, the fronts themselves dissipate, a process called frontolysis. However, changes in the pressure field and the wind as a result of cyclonic activity lead to the development of new fronts and, therefore, to a constant renewal of the process of cyclonic activity along the fronts.

The occurrence of jet streams in the upper part of the troposphere is related to fronts. A distinction is made between the main fronts and secondary fronts, which occur within the air masses of a particular natural zone as a result of certain discontinuities in the main front. They are of little importance in the atmospheric general circulation. There are cases when a front is well developed in the free atmosphere (upper front) but is poorly expressed or not manifested at all near the earth’s surface.

REFERENCES

Palmén, E., and C. Newton. Tsirkuliatsionnye sistemy atmosfery. Leningrad, 1973. (Translated from English.)
Petterssen, S. Analiz i prognozy pogody. Leningrad, 1961. (Translated from English.)

S. P. KHROMOV


Front

 

(1) The highest operational armed forces command in a continental military theater.

The front is designated to carry out operational and operational-strategic missions on one strategic or several operational axes. The missions of the front are carried out by means of operations and general combat, usually with coordination between large units on the front and the commands and large units of other armed services or sometimes independently. The combat composition of the front depends on the mission, conditions, importance, and operational dimensions of the particular axis. Usually a front includes several combined arms, tank, and air armies; separate units of various combat arms and special forces; and operational rear services units, installations, and agencies. A front may be reinforced by units of other armed forces branches and by the reserves of the Supreme Command.

The origin of the front was related to the development of a new form of military action—the operation—and the necessity for centralizing troop command and control. As a result of the experience gained in the Russo-Japanese War of 1904–05, two front directorates were created in the Russian Army for the direction of the troops in the western theater before World War I. At the outset of World War I front commands developed, and in the course of the war the number of fronts increased to five. At that time fronts were designated to fulfill primarily strategic missions. In the Western European armies (Germany, France, and Great Britain) at the beginning of World War I, analogous commands also appeared and were called groups of armies or army groups. In the Red Army during the Civil War of 1918–20 four fronts were created at first and were designated to fulfill strategic missions. As the extent of combat actions expanded and the number of fronts increased (to six or seven), fronts were assigned primarily operational-strategic missions.

In the first days of the Great Patriotic War of 1941–45, the Soviet Supreme Command formed five fronts. During the war the number of fronts varied from ten to 15, depending on the length of the strategic front and the type of action the Soviet forces were engaged in. The fronts fulfilled primarily operational missions; only in certain cases did they carry out strategic missions. Strategic missions were usually assigned to groups of fronts.

In the armies of the capitalist countries during World War II, groups of armies were created as previously. Their composition was determined by the type of mission they were designed to fulfill and the conditions under which they waged combat.

(2) The side of a combat or battle formation that faces the enemy. There are offensive, attack, breakthrough, and defensive fronts. The length of a front of troops (made up of units, large units, and commands) during combat is determined by the situation, combat missions, number of arms, character of the terrain, and other factors.

(3) A line of deployment of armed forces and their point of contact with the enemy in a military theater.

(4) The side of a formation in which the servicemen or vehicles are facing front.

N. N. FOMIN

A list of the fronts of the Soviet armed forces in the Great Patriotic War follows.

Baltic Front (Oct. 10, 1943; from Oct. 20, 1943, Second Baltic Front). Commander, General of the Army M. M. Popov.

First Baltic Front (Oct. 20, 1943-Feb. 24, 1945). Commander, General of the Army A. I. Eremenko (to Nov. 19, 1943); General of the Army I. Kh. Bagramian (to Feb. 24, 1945).

Second Baltic Front (Oct. 20, 1943-Apr. 1, 1945). Commander, General of the Army (from Apr. 20, 1944, Colonel General) M. M. Popov (to Apr. 23, 1944, and Feb. 4–Feb. 9, 1945); General of the Army A. I. Eremenko (Apr. 23, 1944–Feb. 4, 1945); Marshal of the Soviet Union L. A. Govorov (Feb. 9-Mar. 31, 1945).

Third Baltic Front (Apr. 21–Oct. 16, 1944). Commander, Colonel General (from July 28, 1944, General of the Army) I. I. Maslennikov.

Briansk Front (first formation, Aug. 16-Nov. 10, 1941). Commander, Lieutenant General A. I. Eremenko (to Oct. 13, 1941); Major General G. F. Zakharov (to Nov. 10, 1941). Briansk Front (second formation, Dec. 24, 1941; from Mar. 12, 1943, second formation of Reserve Front). Commander, Colonel General Ia. T. Cherevichenko (to Apr. 2, 1942); Lieutenant General F. I. Golikov (to July 7, 1942); Lieutenant General N. E. Chibisov (to July 13, 1942); Lieutenant General K. K. Rokossovskii (to Sept. 27, 1942); Lieutenant General (from Jan. 30, 1943, Colonel General) M. A. Reiter (to Mar. 12, 1943). Briansk Front (third formation, Mar. 28, 1943; from Oct. 10, 1943, Baltic Front). Commander, Colonel General M. A. Reiter (to June 5, 1943); Colonel General M. M. Popov (to Oct. 10, 1943).

Byelorussian Front (first formation, Oct. 20, 1943; from Feb. 24, 1944, first formation of the First Byelorussian Front). Commander, General of the Army K. K. Rokossovskii. Byelorussian Front (second formation, Apr. 5, 1944; from Apr. 16, 1944, second formation of the First Byelorussian Front). Commander, General of the Army K. K. Rokossovskii.

First Byelorussian Front (first formation, Feb. 24, 1944; from Apr. 5, 1944, second formation of the Byelorussian Front). Commander, General of the Army K. K. Rokossovskii.

First Byelorussian Front (second formation, Apr. 16, 1944–May 9, 1945). Commander, General of the Army (from June 29, 1944, Marshal of the Soviet Union) K. K. Rokossovskii (to Nov. 16, 1944); Marshal of the Soviet Union G. K. Zhukov (to May 9, 1945).

Second Byelorussian Front (first formation, Feb. 24–Apr. 5, 1944). Commander, Colonel General P. A. Kurochkin.

Second Byelorussian Front (second formation, Apr. 24, 1944–May 9, 1945). Commander, Colonel General I. E. Petrov (to June 6, 1944); Colonel General (from July 28, 1944, General of the Army) G. F. Zakharov (to Nov. 17, 1944); Marshal of the Soviet Union K. K. Rokossovskii (to May 9, 1945).

Third Byelorussian Front (Apr. 24, 1944–May 9, 1945). Commander, Colonel General (from June 26, 1944, General of the Army) I. D. Cherniakhovskii (to Feb. 18, 1945); Marshal of the Soviet Union A. M. Vasilevskii (Feb. 20–Apr. 26, 1945); General of the Army I. Kh. Bagramian (to May 9, 1945).

Caucasian Front (Dec. 30, 1941; from Jan. 28, 1942, Crimean Front). Commander, Lieutenant General D. T. Kozlov.

Central Front (first formation, July 26–Aug. 25, 1941). Commander, Colonel General F. I. Kuznetsov (to Aug. 7, 1941); Lieutenant General M. G. Efremov (to Aug. 25, 1941). Central Front (second formation, Feb. 15, 1943; from Oct. 20, 1943, first formation of the Byelorussian Front). Commander, Colonel General (from Apr. 28, 1943, General of the Army) K. K. Rokossovskii.

Crimean Front (Jan. 28-May 19, 1942). Commander, Lieutenant General D. T. Kozlov.

Don Front (Sept. 30, 1942; from Feb. 15, 1943, second formation of the Central Front). Commander, Lieutenant General (from Jan. 15, 1943, Colonel General) K. K. Rokossovskii.

Far Eastern Front (formed before the beginning of the war; from Aug. 5, 1945, Second Far Eastern Front). Commander, General of the Army I. R. Apanasenko (to Apr. 25, 1943); Colonel General (from Oct. 26, 1944, General of the Army) M. A. Purkaev (to Aug. 5, 1945).

First Far Eastern Front (Aug. 5–Sept. 3, 1945). Commander, Marshal of the Soviet Union K. A. Meretskov.

Second Far Eastern Front (Aug. 5–Sept. 3, 1945). Commander, General of the Army M. A. Purkaev.

Kalinin Front (Oct. 19, 1941; from Oct. 20, 1943, First Baltic Front). Commander, Colonel General I. S. Konev (to Aug. 26, 1942); Lieutenant General (from Nov. 18, 1942, Colonel General) M. A. Purkaev (to Apr. 25, 1943); Colonel General (from Aug. 27, 1943, General of the Army) A. I. Eremenko (to Oct. 20, 1943).

Karelian Front (Sept. 1, 1941–Nov. 15, 1944). Commander, Lieutenant General (from Apr. 28, 1943, Colonel General) V. A. Frolov (to Feb. 21, 1944); General of the Army (from Oct. 26, 1944, Marshal of the Soviet Union) K. A. Meretskov (to Nov. 15, 1944).

Kursk Front (Mar. 23, 1943; from Mar. 27, 1943, Orel Front). Commander, Colonel General M. A. Reiter.

Leningrad Front (Aug. 26, 1941–May 9, 1945). Commander, Lieutenant General M. M. Popov (to Sept. 5, 1941); Marshal of the Soviet Union K. E. Voroshilov (to Sept. 12, 1941); General of the Army G. K. Zhukov (Sept. 13–Oct. 7, 1941); Major General I. I. Fediuninskii (Oct. 8–26, 1941); Lieutenant General M. S. Khozin (Oct. 27, 1941–June 9, 1942); Lieutenant General (from Jan. 15, 1943, Colonel General; from Nov. 17, 1943, General of the Army; from June 18, 1944, Marshal of the Soviet Union) L. A. Govorov (to May 9, 1945).

Moscow Defense Zone (Dec. 2, 1941–Oct. 15, 1943). Commander, Lieutenant General (from Jan. 22, 1942, Colonel General) P. A. Artem’ev.

Moscow Reserve Front (Oct. 9–12, 1941). Commander, Lieutenant General P. A. Artem’ev.

Mozhaisk Defense Line Front (July 18–30, 1941). Commander, Lieutenant General P. A. Artem’ev.

Northern Front (June 24, 1941; from Aug. 26, 1941, Leningrad Front). Commander, Lieutenant General M. M. Popov.

Northern Caucasus Front (first formation, May 20–Sept. 3, 1942). Commander, Marshal of the Soviet Union S. M. Budennyi. Northern Caucasus Front (second formation, Jan. 24–Nov. 20, 1943). Commander, Lieutenant General (from Jan. 30, 1943, Colonel General) I. I. Maslennikov (to May 13, 1943); Lieutenant General (from Aug. 27, 1943, Colonel General) I. E Petrov (to Nov. 20, 1943).

Northwestern Front (June 22, 1941–Nov. 20, 1943). Commander, Colonel General F. I. Kuznetsov (to July 7, 1941); Major General P. P. Sobennikov (to Aug. 23, 1941); Lieutenant General (from Aug. 28, 1943, Colonel General) P. A. Kurochkin (Aug. 23, 1941–Oct. 5, 1942, and June 23–Nov. 20, 1943); Marshal of the Soviet Union S. K. Timoshenko (Oct. 5, 1942–Mar. 14, 1943); Colonel General I. S. Konev (to June 22, 1943).

Orel Front (Mar. 27, 1943; from Mar. 28, 1943, third formation of the Briansk Front). Commander, Colonel General M. A. Reiter.

Primor’e Group of Forces (Apr. 20, 1945; from Aug. 5, 1945, First Far Eastern Front). Commander, Marshal of the Soviet Union K. A. Meretskov.

Reserve Front (first formation, July 29–Oct. 12, 1941). Commander, General of the Army G. K. Zhukov (July 30–Sept. 12, 1941, and Oct. 8–12, 1941); Marshal of the Soviet Union S. M. Budennyi (Sept. 13–Oct. 8, 1941). Reserve Front (second formation, Mar. 12, 1943; from Mar. 23, 1943, Kursk Front). Commander, Colonel General M. A. Reiter. Reserve Front (third formation, Apr. 10–15, 1943). Commander, Lieutenant General M. M. Popov.

Reserve Armies Front (July 14, 1941; from July 29, 1941, first formation of the Reserve Front). Commander, Lieutenant General I. A. Bogdanov.

Southeastern Front (Aug. 7, 1942; from Sept. 30, 1942, second formation of the Stalingrad Front). Commander, Colonel General A. I. Eremenko.

Southern Front (first formation, June 25, 1941–July 28, 1942). Commander, General of the Army I. V. Tiulenev (to Aug. 30, 1941); Lieutenant General D. I. Riabyshev (to Oct. 5, 1941); Colonel General Ia. T. Cherevichenko (to Dec. 24, 1941); Lieutenant General R. Ia. Malinovskii (to July 28, 1942). Southern Front (second formation, Jan. 1, 1943; from Oct. 20, 1943, first formation of the Fourth Ukrainian Front). Commander, Colonel General A. I. Eremenko (to Feb. 2, 1943); Lieutenant General (from Feb. 12, 1943, Colonel General) R. Ia. Malinovskii (to Mar. 22, 1943); Lieutenant General (from Apr. 28, 1943, Colonel General; from Sept. 21, 1943, General of the Army) F. I. Tolbukhin (to Oct. 20, 1943).

Southwestern Front (first formation, June 22, 1941; from July 12, 1942, first formation of the Stalingrad Front). Commander, Colonel General M. P. Kirponos (to Sept. 20, 1941); Marshal of the Soviet Union S. K. Timoshenko (Sept. 30–Dec. 18, 1941, and Apr. 8–July 12, 1942); Lieutenant General F. Ia. Kostenko (Dec. 18, 1941–Apr. 8, 1942). Southwestern Front (second formation, Oct. 25, 1942; from Oct. 20, 1943, Third Ukrainian Front). Commander, Lieutenant General (from Dec. 7, 1942, Colonel General; from Feb. 13, 1943, General of the Army) N. F. Vatutin (to Mar. 27, 1943); Colonel General (from Apr. 28, 1943, General of the Army) R. Ia. Malinovskii (to Oct. 20, 1943).

Stalingrad Front (first formation, July 12, 1942; from Sept. 30, 1942, Don Front). Commander, Marshal of the Soviet Union S. K. Timoshenko (to July 23, 1942); Lieutenant General V. N. Gordov (to Aug. 12, 1942); Colonel General A. I. Eremenko (to Sept. 30, 1942). Stalingrad Front (second formation, Sept. 30, 1942; from Dec. 31, 1942, second formation of the Southern Front). Commander, Colonel General A. I. Eremenko.

Steppe Front (July 9, 1943; from Oct. 20, 1943, Second Ukrainian Front). Commander, Colonel General (from Aug. 26, 1943, General of the Army) I. S. Konev.

Transbaikal Front (Sept. 15, 1941–Sept. 3, 1945). Commander, Lieutenant General (from May 7, 1943, Colonel General) M. P. Kovalev (to July 12, 1945); Marshal of the Soviet Union R. Ia. Malinovskii (to Sept. 3, 1945).

Transcaucasian Front (first formation, Aug. 23, 1941; from Dec. 30, 1941, Caucasian Front). Commander, Lieutenant General D. T. Kozlov. Transcaucasian Front (second formation, May 15, 1942–May 9, 1945). Commander, General of the Army I. V. Tiulenev.

First Ukrainian Front (Oct. 20, 1943–May 11, 1945). Commander, General of the Army N. F. Vatutin (to Mar. 2, 1944); Marshal of the Soviet Union G. K. Zhukov (to May 24, 1944); Marshal of the Soviet Union I. S. Konev (to May 11, 1945).

Second Ukrainian Front (Oct. 20, 1943–May 11, 1945). Commander, General of the Army (from Feb. 20, 1944, Marshal of the Soviet Union) I. S. Konev (to May 21, 1944); General of the Army (from Sept. 10, 1944, Marshal of the Soviet Union) R. Ia. Malinovskii (to May 11, 1945).

Third Ukrainian Front (Oct. 20, 1943–May 9, 1945). Commander, General of the Army R. Ia. Malinovskii (to May 15, 1944); General of the Army (from Sept. 12, 1944, Marshal of the Soviet Union) F. I. Tolbukhin (to May 9, 1945).

Fourth Ukrainian Front (first formation, Oct. 20, 1943–May 31, 1944). Commander, General of the Army F. I. Tolbukhin (to May 15, 1944). Fourth Ukrainian Front (second formation, Aug. 5, 1944–May 11, 1945). Commander, Colonel General (from Oct. 26, 1944, General of the Army) I. E. Petrov (to Mar. 26, 1945); General of the Army A. I. Eremenko (to May 11, 1945).

Volkhov Front (first formation, Dec. 17, 1941–Apr. 23, 1942). Commander, General of the Army K. A. Meretskov. Volkhov Front (second formation, June 8, 1942–Feb. 15, 1944). Commander, General of the Army K. A. Meretskov.

Voronezh Front (July 9, 1942; from Oct. 20, 1943, First Ukrainian Front). Commander, Lieutenant General (from Jan. 19, 1943, Colonel General) F. I. Golikov (to July 14, 1942, and Oct. 22, 1942–Mar. 28, 1943); Lieutenant General (from Dec. 7, 1942, Colonel General; from Feb. 13, 1943, General of the Army) N. F. Vatutin (July 14–Oct. 22, 1942, and Mar. 28–Oct. 20, 1943).

Western Front (June 22, 1941; from Apr. 24, 1944, Third Byelorussian Front). Commander, General of the Army D. G. Pavlov (to June 30, 1941); Lieutenant General A. I. Eremenko (to July 2, 1941, and July 19–29, 1941); Marshal of the Soviet Union S. K. Timoshenko (July 2–19 and July 30–Sept. 12, 1941); Colonel General I. S. Konev (to Oct. 12, 1941, and Aug. 26, 1942–Feb. 27, 1943); General of the Army G. K. Zhukov (Oct. 13, 1941–Aug. 26, 1942); Colonel General (from Aug. 27, 1943, General of the Army) V. D. Sokolovskii (Feb. 28, 1943–Apr. 15, 1944); Colonel General I. D. Cherniakhovskii (to Apr. 24, 1944).

S. I. ISAEV

front

[frənt]
(meteorology)
A sloping surface of discontinuity in the troposphere, separating air masses of different density or temperature.

front

1. The most prominent face of a building and/or that face which contains the main entrance.
2. The face of a lock through which the bolt or bolts move. It is usually mortised in so as to be flush with edge of door; also called a lock front.

front

front
Warm front.
front
Cold front.
front
Warm occlusion.
front
Cold occlusion.
The bounding surfaces between different air masses. Three main types of fronts are the cold front, warm front, and occluded front.

front

1. Meteorol the dividing line or plane between two air masses or water masses of different origins and having different characteristics
2. Archaic the forehead or the face