Posts Tagged ‘weather’

PostHeaderIcon Riding Sail

describes two different styles of sail that help maintain a boat’s direction into or nearly into the wind during heavy weather or while at anchor. One style is a flat-cut sail with no belly; this is rigged from the backstay and tacked off to one rail at the shrouds. The other style is shaped like a wedge; this is rigged from a boom’s aft end and tacked to each quarter. Also called an anchor sail, backing sail, or stability sail. A riding sail is often used in combination with a sea anchor while at sea in storm conditions.

PostHeaderIcon Inversion

1) A departure from the usual increase or decrease of an atmospheric property with altitude. Inversion usually refers to an increase in temperature with an increase in altitude, which is the opposite of the usual temperature decrease with height. 2) A capsized boat that is completely overturned in the water. See also: turn turtle.

PostHeaderIcon Bermuda High

a large subtropical semi-permanent center of high atmospheric pressure found near Bermuda, in the Western Atlantic Ocean at the Horse latitudes (i.e., sub-tropic latitudes between 30 and 35 degrees North). When this weather system moves farther east it is referred to as the Azores High or, generally, as the North Atlantic High.

PostHeaderIcon Mackerel Sky

a sky covered with cirrocumulus or altocumulus clouds composed of ice crystals, with small vertical extent and in shapes that resemble mackerel scales.

PostHeaderIcon Mares’ Tails

long, well-defined wisps of cirrus clouds that resemble a horse’s tail. According to folklore, mackerel scales and mares’ tails make lofty ships carry low sails. The appearance of these clouds foretells an approaching storm, so sails get lowered to protect boats from the expected high winds. See also: reefing.


About the author:
Bob Roitblat is an avid sailor, writer and professional speaker. If you have any comments about this blog, or you are interested in having Bob to speak at your club, contact the author here: bob@sailorspeak.com

You may also be interested in Bob’s other blog, At The Helm, that is focused on the owners of small-to-medium sized closely-held businesses.

PostHeaderIcon Isobars

lines drawn on a synoptic weather map that connect points of equal barometric pressure. Isobars extend around areas of high and low pressure. Pressure gradient wind speeds are inversely proportional to the distance between the isobars. Tightly spaced isobars indicate strong winds. Widely spaced isobars indicate weaker winds. See also: geostrophic scale.


About the author:
Bob Roitblat is an avid sailor, writer and professional speaker. If you have any comments about this blog, or you are interested in having Bob to speak at your club, contact the author here: bob@sailorspeak.com

You may also be interested in Bob’s other blog, At The Helm, that is focused on the owners of small-to-medium sized closely-held businesses.

PostHeaderIcon Current

water flowing in a given direction due to wind, a venturi effect or gravity, such as river flow. A 1-knot current will show as a definite ripple in the water as it flows past a stationary object, e.g., a buoy or piling. A 3-knot current will cause eddies and swirls for several yards, and a 5-knot current will cause a v-shaped wake up to 50 yards downstream of the stationary object. British and Commonwealth sailors refer to the horizontal movement of water due to the rise and fall of the tide as the stream. See also: drift and set.

PostHeaderIcon Alto

a prefix added to cloud-type names for medium-altitude clouds, between 6,500 and 23,000 feet (2-7 km) above the ground in the middle latitudes or temperate zone; e.g., altostratus. From the Latin word meaning middle.

PostHeaderIcon Cut-off Low

a self-contained or closed, cold-core low pressure weather system that has separated from the jet stream’s westerly flow and that moves independently of it. A cut-off low may remain nearly stationary for days, or on occasion may move westward, opposite to the prevailing flow aloft. The weather conditions within a cut-off low are usually unstable and can produce significant precipitation. There are generally light winds to the south of a cutoff, in the northern hemisphere, and stronger winds to the north. Also known as a subtropical low. Compare to: cold eddie.

PostHeaderIcon Unstable

as it relates to an air mass, describes air that is warmer than the surrounding air and that is rising. See also: low-pressure system. Compare to: stable.

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