Occluded front

A cyclone in the early stages of occlusion
The symbol of an occluded front

An occluded front is formed during the process of cyclogenesis when a cold front overtakes a warm front. When this occurs, the warm air is separated (occluded) from the cyclone center at the Earth's surface. The point where the warm front and the occluded front meet (and consequently the nearest location of warm air to the center of the cyclone) is called the triple point.[1]

There are two types of occlusion, warm and cold. In a cold occlusion, the air mass overtaking the warm front is cooler than the cool air ahead of the warm front, and plows under both air masses. In a warm occlusion, the air mass overtaking the warm front is not as cool as the cold air ahead of the warm front, and rides over the colder air mass while lifting the warm air.

A wide variety of weather can be found along an occluded front, with thunderstorms possible, but usually their passage is associated with a drying of the air mass. Additionally, cold core funnel clouds are possible if shear is significant along the cold front. Occluded fronts are indicated on a weather map by a purple line with alternating semicircles and triangles pointing in direction of travel. Occluded fronts usually form around mature low pressure areas.


  1. ^ Djurić, D: "Weather Analysis". Prentice Hall, 1994. ISBN: 0-13-501149-3.

Schultz, D. M., and G. Vaughan, 2011: Occluded fronts and the occlusion process: A fresh look at conventional wisdom. Bull. Amer. Meteor. Soc., 92, 443–466, ES19–ES20.

See also

External links

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Look at other dictionaries:

  • occluded front — ☆ occluded front n. Meteorol. the front formed when a warm front is overtaken by a cold front and an air mass is forced aloft up the warm front or cold front surface …   English World dictionary

  • occluded front — ► NOUN ▪ a composite weather front produced when a cold front catches up with a warm front, so that the warm air in between them is forced upwards …   English terms dictionary

  • occluded front — Fronts formed by the merging of cold and warm fronts. If a cold front overtakes a warm front, the result would be an occluded front. Also known as a frontal occlusion or an occlusion. See also front …   Aviation dictionary

  • occluded front — noun An occluded front occurs when a cold front overtakes a warm front at the surface and a temperature contrast exists between the advancing and retreating cold air masses …   Wiktionary

  • occluded front — occlud′ed front′ n. mer a composite front formed when a cold front overtakes a warm front and forces it aloft; occlusion • Etymology: 1965–70 …   From formal English to slang

  • occluded front — Meteorol. a composite front formed when a cold front overtakes a warm front and forces it aloft. Also called occlusion. [1965 70] * * * …   Universalium

  • occluded front — /əkludəd ˈfrʌnt/ (say uhkloohduhd frunt) noun Meteorology the residual front after the cold front of a depression has overtaken the warm front and the warm sector has been lifted. Also, occlusion …   Australian English dictionary

  • occluded front — noun (meteorology) a composite front when colder air surrounds a mass of warm air and forces it aloft • Syn: ↑occlusion • Topics: ↑meteorology • Hypernyms: ↑front …   Useful english dictionary

  • occluded front — noun Meteorology a composite front produced by occlusion …   English new terms dictionary

  • occluded front — noun Date: circa 1938 occlusion 2 …   New Collegiate Dictionary

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