The local variation of the wind vector or any of its components in a given direction. The vertical shear can be expressed in terms of height ∂V/∂z or of pressure ∂V/∂p as the vertical coordinate.

The most common system for representing wind speed, to the nearest 5 knots, in symbolic form on synoptic charts.

It consists of drawing the appropriate number of half-barbs, barbs, and pennants from the end of the wind-direction shaft. In this system, a half-barb represents 5 knots, a barb 10 knots, and a pennant 50 knots.

In aviation terminology, the motion of an aircraft in flight when a crosswind causes its heading to differ from the course.

(Or, simply, cloud chamber.) A device that renders visible the paths of high energy subatomic particles.

A supersaturated vapor condition is created in a chamber filled with dust-free air by a sudden adiabatic expansion and cooling. In this environment, the small ions formed along the path of a high energy particle act as effective condensation nuclei. The line of droplets so formed can be used to mark the path.

(Also spelled bagyu or bagyio.) In the Philippine Islands, the name given to any severe tropical cyclone; derived from the city of Baguio, where a record 24-h rainfall of 46 in. (~117 cm) occurred during the passage of a tropical cyclone in July 1911.

Long-wave disturbances of the ocean surface driven by atmospheric pressure variations associated with fast-moving weather events such as thunderstorms, squalls, and other storm fronts.

(Also called true solar day.) The interval of time between two successive transits of the sun across a meridian.

(Also called optical array probe.) An optical particle probe that records the size and shape of the shadow of each particle that intercepts and attenuates the illumination by a laser beam.

A low-level, horizontal, wedge-shaped arcus cloud associated with a convective storm's gust front (or occasionally a cold front).

The shelf cloud is attached to the convective storm's cloud base. Rising motion can be seen in the leading (outer) part of the shelf cloud, while the underside appears turbulent and tattered.

(Also called planetary wave.) A wave on a uniform current in a two-dimensional nondivergent fluid system, rotating with varying angular speed about the local vertical (beta plane).

(Also called thermal belt, thermal zone, green belt, verdant zone.) That warmest part of a slope above a valley floor lying between the layer of cold air that forms over the valley floor on calm, clear nights and the cold hilltops or plateaus.

1. A two-dimensional barotropic disturbance in a fluid having one or more discontinuities in the vorticity profile.

2. A wave propagated along the surface of a semi-infinite elastic solid and bearing certain analogies to a surface gravity wave in a fluid.

(Derived from Arabic mausim, a season.) A name for seasonal winds.

It was first applied to the winds over the Arabian Sea, which blow for six months from northeast and for six months from southwest, but it has been extended to similar winds in other parts of the world. 

A long, narrow, and transient corridor of strong horizontal water vapor transport that is typically associated with a low-level jet stream ahead of the cold front of an extratropical cyclone.

(Also called landfast ice.) Sea ice that is immobile due to its attachment to a coast, usually extending offshore to about the 20-m isobath.

In protected bays and inlets, fast ice is smooth and level, typically reaching a thickness of between 2 and 2.5 m. Along exposed coastlines, fast ice may be greatly deformed.

A low pressure system that is often fast-moving, has low moisture content, and originates in western Canada (in or near Alberta province). In the wintertime, it may be associated with a narrow but significant band of snowfall, and typically affects portions of the plains states, Midwest, and East Coast.

Localized, convective snow bands that occur in the lee of lakes when relatively cold airflows over warm water.

In the United States this phenomenon is most noted along the south and east shores of the Great Lakes during arctic cold-air outbreaks.

Any narrow extension of a glacier or ice shelf, such as a projection floating in the sea or an outlet glacier of an ice cap.