Windward and leeward

"Windward" redirects here. For the regional airline based in the Netherlands Antilles with the callsign "Windward", see Winair.

"Alee" redirects here. For the Canadian country music singer-songwriter, see Alee (singer).

File:Upwind downwind example.png

Example image showing definitions of windward (upwind) and leeward (downwind).

Windward is the direction upwind (toward where the wind is coming from) from the point of reference. Leeward is the direction downwind (or downward) from the point of reference. The side of a ship that is towards the leeward is its lee side. If the vessel is heeling under the pressure of the wind, this will be the "lower side". During the age of sail, the term weather was used as a synonym for windward in some contexts, as in the weather gage.

Pronunciation

The traditional nautical pronunciations are the elided forms /ˈljuːərd/ and /ˈwɪnərd/, but this is regarded as old-fashioned. The literal pronunciations, /ˈliːwərd/ and /ˈwɪndwərd/, are more common. The pronunciation for the Leeward and Windward Islands and the Leeward Antilles is normally the latter form.

Origin

The term lee derives from Old English hleo, shelter, and was in use at least as early as 900 AD.

The word aloof is a related term derived from loof, old English for "weather gage" or "windward direction", probably from the Dutch word loef, “the weather side of a ship." Aloof was originally a nautical order to keep the ship's head to the wind, for example to avoid a lee-shore, but it has since taken a figurative meaning of "at a distance, or reserve suggesting consciousness of superiority." It is still in use in german sailors' language as "LUV." Note also the wind-related words loft in English and luft in modern German.

Meteorological significance

Leeward and windward refer respectively to what a game stalker would call downwind and upwind. The terms are used by seamen in relation to their ships but also in reference to islands in an archipelago and to the different sides of a single island. In the latter case, the windward side is that side of an island subject to the prevailing wind, and is thus the wetter side (see orographic precipitation). The leeward side is the side protected by the elevation of the island from the prevailing wind, and is typically the drier side of an island. Thus, leeward or windward siting is an important weather and climate factor on oceanic islands.

In the case of an archipelago, windward islands are upwind and leeward islands are the downwind ones.

Other significance

In aviation, downwind refers to a portion of an aircraft's landing pattern. The long side parallel to the runway but flown in the opposite direction is called the downwind leg.

On land, downwind is often used to refer to a situation where a point source of air pollution or a scent moves from a point upwind, along the direction of the wind, to the point of the observer.

Downwind has specific connotations in industrial cities in the English North, where less desirable and less expensive housing was often situated to the leeward of steelworks, blast furnaces, mills, or other sources of intense pollution. Hence in some cities it is used as a generic, slang, pejorative and discriminatory term for less wealthy areas or their inhabitants.

Nautical and naval

Main article: Sailing

Windward and leeward directions are important factors (points of sail) to consider when sailing a sailing ship. Other terms with broadly the same meaning are widely used, particularly upwind and downwind, and many variations using the metaphor of height ("come up", "drop down", "we're pointing higher than them", "head below that mark", and so on).

The windward vessel is normally the more maneuverable vessel. For this reason, rule 12 of the International Regulations for Preventing Collisions at Sea stipulates that the windward vessel gives way to the leeward vessel. Similarly, a square rigged warship would often try to enter battle from the windward direction (or "hold the weather gauge"), thus gaining an important tactical advantage over the opposing warship – the warship to windward could choose when to engage and when to withdraw. The opposing warship to leeward could often do little but comply without exposing itself unduly.

This was particularly important once artillery was introduced to naval warfare. The ships heeled away from the wind so that the leeward vessel was exposing part of her bottom to shot. If damaged "between wind and water" (i.e., in the exposed section of the hull) she was consequently in danger of sinking when on the other tack, as happened to some ships of the Spanish Armada at the Battle of Gravelines.

See also

• Barlavento (Windward) and Sotavento (Leeward) in Cape Verde Islands
• Downstream and upstream
• Lee shore
• Northwestern Hawaiian Islands, also known as Leeward Islands
• Windward Islands, Leeward Islands and Leeward Antilles (in the Lesser Antilles)
• Windward Islands and Leeward Islands (in the Society Islands)
• Foehn wind

External links

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