SHEAR ENERGY

The phenomena we refer to as SHEAR can display at least as much variety as all the other, better known forms of lift.  They might be rapid and turbulent, or so gentle that their effect is scarcely noticeable. They may or may not be marked by contrasting degrees of haze and clarity, by the full range of cumulus type clouds, or by dust devils or a line of blowing dust.  A shear may operate in only one confined area, or can run continuously over the horizon.  A line of soarable lift may be no wider than a wingspan, but also could be miles across!  Whether weak or strong, a shear line may provide solid, smooth lift; it might consist of a series of individual thermals (blue or otherwise); or it could be no more organized than intermittent bundles of turbulence rolling upward.  Shear lines may extend perfectly straight,  arc off into the distance as a huge, uniform curve, or possibly meander back and forth, snakelike.  They may be workable only at very low altitude or only far above the ground.   They may favor the highest terrain or the lowest, and some shears can remain consistent and strong from near sea level all the way up to very great height.  If wind is stronger on one side of a line than the other, shears tend to migrate sideways, but a change in wind strengths can reverse this drift.  The possibilities are endless, and the uncertainty can be too.Flows can come together at any angle, with their interface extending vertically or diagonally.  Shears may behave as multiple pressure waves, roughly parallel, with each line oriented between winds from about the same direction but of unequal speeds.  (Shears of that type are apt to march downwind rather quickly.)  Where two air masses collide head-on the lift might be dramatic at very low altitudes, even if the surface wind on either side is light.