Windward () and leeward () are terms used to describe the direction of the wind. Windward is ''upwind'' from the point of reference, i.e. towards the direction from which the wind is coming; leeward is ''downwind'' from the point of reference, i.e. along the direction towards which the wind is going. The side of a ship that is towards the leeward is its "lee side". If the vessel is heeling under the pressure of

crosswind A crosswind is any wind that has a perpendicular component to the line or direction of travel. This affects the aerodynamics of many forms of transport. Moving non-parallel to the wind's direction creates a crosswind component on the object and th ...

, the lee side 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 The weather gage (sometimes spelled weather gauge) is the advantageous position of a fighting sailing vessel relative to another. It is also known as "nautical gauge" as it is related to the sea shore. The concept is from the Age of Sail and is no ...

''. Because it captures rain, the windward side of a mountain tends to be wet compared to the leeward it blocks.

Origin

The term "lee" comes from the middle-low German word // meaning "where the sea is not exposed to the wind" or "mild". The terms Luv and Lee (engl. Windward and Leeward) have been in use since the 17th century.

Usage

Windward and leeward directions (and the points of sail they create) are important factors to consider in such wind-powered or wind-impacted activities as

sailing Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the ''water'' (sailing ship, sailboat, raft, windsurfer, or kitesurfer), on ''ice'' (iceboat) or on ''land'' (land yacht) over a chosen cou ...

wind-surfing Windsurfing is a wind propelled water sport that is a combination of sailing and surfing. It is also referred to as "sailboarding" and "boardsailing", and emerged in the late 1960s from the aerospace and surf culture of California. Windsurfing ga ...

, gliding,

hang-gliding Hang gliding is an air sport or recreational activity in which a pilot flies a light, non-motorised foot-launched heavier-than-air aircraft called a hang glider. Most modern hang gliders are made of an aluminium alloy or composite frame covered ...

, and parachuting. Other terms with broadly the same meaning are widely used, particularly ''upwind'' and ''downwind''.

Nautical

Among sailing craft, the windward vessel is normally the more maneuverable. For this reason, rule 12 of the International Regulations for Preventing Collisions at Sea, applying to sailing vessels, stipulates that where two are sailing in similar directions in relation to the wind, the windward vessel gives way to the leeward vessel. Handling of the leeward vessel may be severely affected if she passes into the lee of the windward vessel. Handling of the windward vessel is free of such complication.

Naval warfare

In naval warfare during the Age of sail, a vessel always sought to use the wind to its advantage, maneuvering if possible to attack from windward. This was particularly important for less maneuverable square-rigged warships, which had limited ability to sail upwind, and sought to "hold the

" entering battle. This was particularly important once

artillery Artillery is a class of heavy military ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during siege ...

was introduced to naval warfare. Ships heel away from the wind, so the leeward vessel would expose more of her topsides to shot, in extreme cases even part of her bottom.

Describing islands

The terms windward and leeward are used in reference both to sides (and climates) of individual islands and relative island locations in an

archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands. Examples of archipelagos include: the Indonesian Arc ...

. The windward side of an island is subject to the

prevailing wind In meteorology, prevailing wind in a region of the Earth's surface is a surface wind that blows predominantly from a particular direction. The dominant winds are the trends in direction of wind with the highest speed over a particular point o ...

, and is thus the wetter (see

orographic precipitation Orography is the study of the topographic relief of mountains, and can more broadly include hills, and any part of a region's elevated terrain. Orography (also known as ''oreography'', ''orology'' or ''oreology'') falls within the broader discip ...

). The leeward side is the side distant from or physically in the lee of the prevailing wind, and typically the drier. In an archipelago ''windward islands'' are upwind and ''leeward islands'' are downwind of the prevailing winds, such as the

trade winds The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisp ...

of the Atlantic and Pacific oceans.

References