Wave Lift
Lee waves occur when a wind of 25 knots (46 km/h) blows over a mountain. Provided that there is a steady increase in wind strength with altitude without a significant change in direction, standing waves may be created. They were discovered by a glider pilot, Wolf Hirth, in 1933. These waves reach heights much greater than the original obstruction and so can permit gliders to climb to the stratosphere. Pilots use supplementary oxygen to avoid hypoxia because gliders do not have pressurized cockpits. This lift is often marked by long, stationary lenticular (lens-shaped) clouds lying perpendicular to the wind. A mountain wave was used to set the record for highest altitude by a glider when Steve Fossett and Einar Enevoldson, wearing pressure suits, soared to an altitude of 50,699 feet (15,453 m) on August 29, 2006 over El Calafate, Argentina in their modified DG-505. The current world distance record of 3,008 km (1,869 statute miles) by Klaus Ohlmann (set on 21 January 2003) was also flown using mountain waves in South America.
A rare wave phenomenon is known as Morning Glory, a roll cloud producing strong lift. Pilots near Australia's Gulf of Carpentaria make use of it in springtime.
Birds have been observed using wave lift to cross mountainous regions.
Read more about this topic: Lift (soaring)
Famous quotes containing the words wave and/or lift:
“I hear
the tide turning. Last
eager wave over-
taken and pulled back
by first wave of the ebb.”
—Denise Levertov (b. 1923)
“For there is no friend like a sister
In calm or stormy weather;
To cheer one on the tedious way,
To fetch one if one goes astray,
To lift one if one totters down,
To strengthen whilst one stands.”
—Christina Georgina Rossetti (1830–1894)