Ingeography andseamanship,windward (/ˈwɪndwərd,ˈwɪnərd/) andleeward (/ˈliːwərd,ˈljuːərd/) are directions relative to thewind. Windward isupwind from the point of reference, i.e., towards the direction from which the wind is coming; leeward isdownwind 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 isheeling under the pressure ofcrosswind, the lee side will be the "lower side". During theAge of Sail, the termweather was used as a synonym forwindward in some contexts, as in theweather gage.
Since it capturesrainfall, the windward side of amountain tends to be wetter than the leeward side it blocks. The drier leeward area is said to be in arain shadow.
The term "windward" has roots in both Low German and Old English. The word "lee", which means a place without wind, comes from the Old Norse "hle" for "cover" and has been used in marine navigation in Germany since medieval times. The word "wind," meaning "air in motion," comes from Proto-Germanic *winda- and has evolved over time, with pronunciation changes influenced by similar words like "windy." The word "wind" has been associated with emptiness and vanity since the late 13th century. Additionally, "wind" has been used figuratively in phrases like "which way the wind blows" to indicate the current state of affairs. The suffix "-ward," meaning "toward," is an adverbial suffix in Old English derived from Proto-Germanic *werda-, which itself comes from the PIE root *wer- meaning "to turn, bend." The original notion of "-ward" is "turned toward."[1][2]
Windward and leeward directions (and thepoints of sail they create) are important factors to consider in such wind-powered or wind-impacted activities assailing,wind-surfing,gliding,hang-gliding, andparachuting. Other terms with broadly the same meaning are widely used, particularlyupwind anddownwind.[3]
Among sailing craft, the windward vessel is normally the more maneuverable. For this reason, rule 12 of theInternational 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.[4]
In naval warfare during theAge 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 maneuverablesquare-rigged warships, which had limited ability to sail upwind, and sought to "hold theweather gage" entering battle.[5]
This was particularly important onceartillery was introduced to naval warfare. Ships heel away from the wind, so the leeward vessel would expose more of hertopsides to shot, in extreme cases even part of her bottom.[6]
The terms windward and leeward are used in reference both to sides (and climates[7]) of individual islands and relative island locations in anarchipelago. The windward side of an island is subject to theprevailing wind, and is thus the wetter (seeorographic precipitation). The leeward side is the side distant from or physically in the lee of the prevailing wind, and typically the drier.
In an archipelagowindward islands are upwind andleeward islands are downwind of the prevailing winds, such as thetrade winds of the Atlantic and Pacific oceans.