English

Short lines drawn on a CHART or MAP for representing RELIEF. These lines are drawn in the direction of the SLOPE and intensified on the shaded side of the feature assuming the area is illuminated from the north-west. Unlike the CONTOUR LINES, they give no indication of the actual HEIGHT of LAND above SEA LEVEL. See also HILL SHADING.

PRECIPITATION of small balls or pieces of ICE (HAILSTONES) with a diameter ranging from 5 to 50 mm (0.2 to 2.0 in) or sometimes more, falling either separately or agglomerated into irregular lumps.

Globule or piece of ICE, with a diameter varying between 5 and 50 mm or even more, the fall of which constitutes HAIL. Hailstones consist almost entirely of transparent ICE, or of a series of LAYERS of transparent ICE with a thickness of at least 1 mm, alternating with translucent LAYERS.

In PHOTOGRAPHY, a spreading of a photogra­phic IMAGE beyond its proper boundaries, due especially to REFLECTION from the side of the film or plate support opposite to that on which the EMULSION is coated. Par­ticularly noticeable in PHOTOGRAPHS of bright objects against a darker background.

In PHOTOGRAPHY or printing, a technique in which the solid IMAGE is broken up by the use of a screen into evenly spaced dots of equal density but of varying size. This gives an illusion of con­tinuous tone.

Group of optical PHENOMENA, in the form of rings, arcs, pillars or bright spots, produced by the REFRACTION or REFLECTION of light by ice cry­stals suspended in the ATMOSPHERE (cirriform CLOUDS, ICE FOG, etc.).

HALO much less frequent and always less luminous than the SMALL HALO. It comprises a faintly luminous ring centered on the SUN or MOON and has an apparent radius of 46°.

White, or mostly white, luminous ring of 22° radius with the luminary at its centre. The small halo shows a faint red fringe on the inside and, in some rare cases, a violet fringe on the outside. The portion of the sky inside the ring is conspicuously darker than the rest of the sky.

A vertical GRADIENT of salinity (which is usually positive) in some LAYER of the body of water, which is appreciably greater than the GRADIENTS above and below it.

A natural or artificially improv­ed body of water providing protection for vessels, and generally ANCHORAGE and docking facilities. See also PORT.