Aviation Glossary

At Dauntless, our editorial staff maintains the web's largest unified glossary of aviation terms. This glossary is built from a combination of official, quasi-official, and proprietary sources (including original material that we develop oursselves). Uniquely, we often provide multiple definitions of a given term so that you can find that which best applies to you. In order to maximize your learning efficiency, this glossary (and similar ones for our international users) is incresingly fully integrated into our aviation learning apps, including our FAA written test prep and FAA practical test prep software and apps. If you like this glossary, you'll love them with their polished learning environments and world's best and clearest content (please do give them a try.).

Trough

In meteorology, an elongated area of relatively low atmospheric pressure; usually associated with and most clearly identified as an area of maximum cyclonic curvature of the wind flow (isobars, contours, or streamlines); compare with ridge.

source: FAA Aviation Weather for Pilots (AC 00-6A)

In weather, an elongated area of low pressure with no rotative motion.

source: FAA Balloon Flying Handbook (FAA-H-8083-11)

The low area between two wave crests.

source: FAA Seaplane Handbook (FAA-H-8083-23)

An elongated area of relatively low atmospheric pressure, usually not associated with a closed circulation, and thus used to distinguish from a closed low. The opposite of ridge.

source: NOAA National Weather Service Glossary

Ace Any FAA Written Test!

	Actual FAA Questions / Free Lifetime Updates
	The best explanations in the business
	Fast, efficient study.

Pass Your Checkride With Confidence!

	FAA Practical Test prep that reflects actual checkrides.
	Any checkride: Airplane, Helicopter, Glider, etc.
	Written and maintained by actual pilot examiners and master CFIs.

The World's Most Trusted eLogbook

	Be Organized, Current, Professional, and Safe.
	Highly customizable - for student pilots through pros.
	Free Transition Service for users of other eLogs.

Disclaimer: While this glossary in most cases is likely to be highly accurate and useful, sometimes, for any number of editorial, transcription, technical, and other reasons, it might not be. Additionally, as somtimes you may have found yourself brought to this page through an automated term matching system, you may find definitions here that do not match the cotext or application in which you saw the original term. Please use your good judgement when using this resource.