EVEN MORE on STREETS

     Up high, especially in humid weather with big vertical development of cumulus, a peculiar hazard exists that must be accounted for.   The scientific name for it is 'latent heat of condensation', but a term coined by hang-gliding and paragliding pilots is more descriptive and helpful for our purpose:  'CLOUD SUCK'.   As rising air reaches dew point the very process of gas becoming water vapor releases heat, instantly making that air more buoyant.   In other words, just when you're topping out near cloud base the lift suddenly strengthens.   If  'cloud suck'  is a problem, you are already too close to cloud base for safety - and probably illegal, too.   Pilots have had to bail out because of this phenomenon.   (When tempted to cheat on separation from clouds, remember also the possibility of faster aircraft overtaking you from behind, and maybe other hard-to-see sailplanes coming head-on!)     To transform this problem into an advantage, speed up.   Turn all that vertical energy into forward speed.   This is your opportunity to GO!     High up within a powerful street, you might be able to carry a great deal of speed, and things will happen fast.   You'll be able to see much less of clouds ahead, or of the surrounding landscape, and may need to use cloud shadows to plan your immediate route.   When doing so, bear in mind that shadows cover more area than the clouds themselves, due to sun angle and vertical development of cumulus, and that shadows alone give no indication of the strength or age of thermals that have produced the clouds.   (Also, widespread shading can reduce and eventually kill convective lift.)