Joe Wurts1 Finding and Recognizing Thermals Joe Wurts

2 Topics of Discussion u Thermal Theory u Application u Thermal Sources u Non-Thermal Lift

Joe Wurts3 Thermal Theory - Basics u Basic definition: lighter than the surrounding air u Thermal shapes –Column –Bubble –Disorganized blob –Streets

Joe Wurts4 Thermal Theory - Climate Influences u Humidity u Ground moisture u Lapse rate u Inversion height u Cloudiness

Joe Wurts5 Thermal Theory - Characteristics u Feeds from warm air near the ground u Drifts with the wind u Attraction to other thermals u Thermal aspect ratio

Joe Wurts6 Application - Clues to Finding Thermals u Detecting thermal inflow –Inflow signs –Wind lulls, changes –Wind shifts »Do not confuse with thermal inflow u Ground signs –Look for the “third vector” The “third vector” Wind Inflow Wind Thermal Inflow

Joe Wurts7 Application - The Third Vector u Mental vector math = Direction to thermal u What to look for –Temporary changes in the wind »Direction »Speed The “third vector” Wind Inflow

Joe Wurts8 Application - Practical Guidelines u Sharply defined upwind edge u Diffuse downwind edge u Convergence zones u Angled streets Wind

Joe Wurts9 Application - Perspective Challenges u Confusion between range and altitude u Elevation angle confusion Wind

Joe Wurts10 Application - Hints on Recentering u Turn tighter in the stronger lift u Constantly reevaluate on each circle u Be wary of subconscious upwind drift u Effects of horizontal wind shear Wind

Joe Wurts11 Thermal Sources u Heating sources –Drier ground –Radiation sources u Terrain influences –Tree lines –Hills Wind

Joe Wurts12 u Wave –Conditions necessary –When likely u Shear line u Hydraulic wave u Dynamic soaring Non-Thermal Lift