Vertical draft

In meteorology, an updraft (British English: up-draught) is a small-scale current of rising air, often within a cloud.^[1]

Overview

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 is either warmer or less dense than itself. The converse will occur for a mass of cool air, and is known as

. 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 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

. Downburst damage can be differentiated from that of a tornado because the resulting destruction is circular and radiates away from the center. Tornado damage radiates inward, towards the center of the damage.

The term "downdraft" can also refer to a type of backdraft which occurs through chimneys which have fireplaces on the lowermost levels (such as basements) of multi-level buildings. It involves cold air coming down the chimney due to low air pressure, and makes it hard to light fires, and can push soot and carbon monoxide into domiciles.

See also

• FAA
  ) and abroad
• NOAA's National Weather Service
  )
• Low level windshear alert system
• Atmospheric thermodynamics
• Lee waves
• New Zealand National Airways Corporation Flight 441 — airplane crash linked to severe downdraft
• forward flank downdraft
• Thermal

References

External links

• National Science Digital Library - Downdraft
• the Microburst Windshear