[uhp-draft, -drahft]
the movement upward of air or other gas.

1400–50; late Middle English; see up-, draft

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Based on the Random House Dictionary, © Random House, Inc. 2014.
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Word Origin & History

"rising air current," 1909, from up + draft (n.).
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Science Dictionary
updraft   (ŭp'drāft')  Pronunciation Key 
An upward current of warm, moist air. With enough moisture, the current may visibly condense into a cumulus or cumulonimbus cloud. Compare downdraft.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Britannica


in meteorology, upward-moving and downward-moving air currents, respectively, that are due to several causes. Local daytime heating of the ground causes surface air to become much warmer than the air above, and, because warmer air is less dense, it rises and is replaced by descending cooler air. The vertical ascending current, called a thermal, may reach an altitude of 3 km (2 miles) or more. The greater the radius of the thermal, the higher it is likely to ascend. Updrafts and downdrafts also occur as part of the turbulence that is created when air passes over topographic barriers such as mountains.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
The hawk drifted, riding an updraft, its screeching sound carrying over the
  thrum of the waves.
The air in the downdraft wrapped around the air in the updraft.
It was being sucked into the updraft of a storm cloud.
The fire's updraft, for example, sucks in air and generates winds that fan the
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