Keeping it up.  

Lift is what keeps sailplanes flying and is where you find it.  Finding it depends on the development of your 'bird brain'.  Glider pilots smile when asked 'what do you do when the wind quits?'.  It's a good question, but not related to the most common type of lift, which results from thermals.  In fact, too much wind may make thermals difficult, if not impossible to use.  However there are types of lift there are partially or completely dependent on wind, namely ridge and wave, and these can result in spectacular soaring.

Thermal lift

Thermals result from a combination of unstable atmospheric conditions and solar heating.  These buoyant plumes result in mixing of the atmosphere and combine into larger plumes and columns of rising air.  Like soaring birds, gliders circle within the columns and climb.  The tops of these columns are frequently marked by the white, puffy cumulus clouds, though some days are quite soarable without any cloud markers.  Between the thermals, air is descending, what glider pilots call 'sink'.  Hey, sink happens.  It how effectively you deal with the lift and sink that allows you to fly for distances, or wind up back on the ground.  In some of the videos, you may notice a chirpy beeping sound.  That an audio indication of lift and the higher the pitch, the stronger the lift.  A low pitched tone indicates sinking air.  Using audio allows the pilot to keep eyes off the instruments and ever watchful for other gliders and aircraft, and visual indications of lift in the distance.  Circling gliders, birds, rising smoke, dust devils, clouds and their shadows are some of the important indicators.

L-13 Blanik Thermaling, Saskatoon, Saskatchewan

Puchaz Thermaling, Czech Republic

Very Strong Thermal, pilot banks up to 70 degrees to try and center in the very tight core.

Ridge Running

When the wind gets up, those soaring sites that are positioned near geographic ridge lines often produce a vertical deflection of the wind, upwards.  These ridge lines can be modest hills or mountain ranges.  The first recorded 1,000 mile flight was made along the Allegheny/Appalachian mountains ridges.  Instead of climbing high, the gliders position themselves in front of, or above the ridge lines and flight mostly perpendicular to the wind, and cruise at high speed often just above the tree tops.  The flight can be physically demanding and rough.  It's prudent to keep the belts really tight. 

Ridge flying the Cotswolds north of London, England

Ridge Soaring Mifflin, PA, notice the long, long ridges

Glider Ridge Run, Long Mynd.  Two gliders running the ridge near the border between England and Wales.

The Wave

Imagine a river of air weighing hundreds of millions of tons.  Imagine this river of air passing over hills and mountains.  It rises, then falls as it moves over these obstacles.  As it falls, it compresses, warms, and bounces and flows back up, repeating this pattern for sometimes as many as fifteen oscillations downwind.  Here in Colorado we often have days in mid-winter when the smooth lenticular clouds mark this river of air and we feel the warmth of the compressing air.  Sailplanes can park or cruise in a rising sections of this river and climb to great heights and long distances.  The Colorado altitude record for gliders is 44,000 feet above sea level.  The world record is over 51,000 feet, done in Argentina. This is 'the wave'.

Wave Soaring in Zar Poland, Sebastian Kawa does some local wave soaring with friends.

Talgarth Wave, Wave in the Welsh mountains.

Pacific Coast Wave, wave soaring the Santa Cruz and Galiban Mountains out of Hollister, California.  Mix of videos, stills, and computer flight traces. Part 2

Wave flying Omarama, who says Kiwi's are flightless?

Putting it All Together

Although many flights may use only one type of lift, conditions and locations may offer quite a variety.

'Glider on 'The Ridge' Another flight from Mifflin, PA, that uses all three of the above types of lift, thermal, ridge, and wave.  A demonstration that lift is indeed where you find it.

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