Show Thermals Are Lift For Sailplanes As mentioned in the last article article article ar ar- on gliding soaring the most used often-used source of lift is the thermal which occurs in almost every part of the world THERMALS are nothing but rising air masses which have been heated indirectly by the suns sun's warming of an open field a city the side of ahill a ahill ahill hill or mountain taking the suns sun's rays directly etc They form on sunny days and are usually denoted by small cumulous clouds The best days are when the cumulous cumulous lous clouds do not overbuild overbuild overbuild over build into which thunderheads are too dangerous for gliders and powered planes for that matter BUT THERE are other kinds of lift The two most frequently used after thermaLs thermals thermals ther- ther maLs are ridge lift and wave lift Ridge lift results from wind deflection off a slope or ridge Good pilots can soar up and down their length for many miles on good days taking advantage of the uplift offered by the deflected wind ONE MUST be careful to always turn outward from the ridge fur sometimes theair the theair theair air current closest to it willbe will willbe willbe be downward and also the soaring pilot can easily mis- mis the distance he needs to turn That happened a few months ago in California and a pilot was killed when he apparently attempted to turn too sharply after underestimating his turn radius He stalled falling into the cliffside WAVE LIFT results from wind blowing across moun mouri Interestingly it acts just as waves in water do Usually there is a gap called the Foehn Gap between the lee side of mountains and the first upward wave of air Often these waves can be spotted because cumulous clouds from where the rising air condenses This is where lift can be used to gail gall alti alti- tude Sometimes wave lift goes quite in high some cases inthe in inthe inthe the west to more than twenty thousand feet SOARING pilots fly up and down such a wave They climb in the first fist lee wave encountered encountered encountered and then glide at the best speed fly until they reach the next wave These waves of air push up and down to the lee side of the mountain for miles and miles Thus one can sometimes sometimes sometimes some some- times glide downwind from one wave to another for many miles or can on such days soar up and down one of these waves for long perio periods THERE IS often lift at the seacoast but unless there is isa isa isa a ridge it is not as productive as wave lift though much gliding is being done in Florida Florida Florida Flori Flori- da these days utilizing both thermals and the coast never high in Florida California is a wonderful state for soaring as are Colorado Colorado Colo Color rado Nevada Texas and many of the western states NOT LONG ago a pilot flew over miles from Nevada to Mexico often at feet which shows what can be bedone bedone bedone done in this part of the coun coun- try |