thermals
Warm ascending currents
Thermals are columns of rising warm air that birds and gliders use to gain altitude without expending energy.
Pilots and hawks circle within thermals to climb.
The word also refers to thermal underwear—insulating garments worn in cold weather: I packed thermals for the ski trip.
Both senses connect to heat retention or movement.
Rising effortlessly upward
- glidingEngineless aerial movement
- convectionHeat transfer via motion
- buoyancyFluid's upward resistance
- liftMechanism for vertical transport
paragliding · hang-gliding · sailplane · circling · altitude · cumulus · hawk · vulture
Insulating underwear for cold
- underwearClothing worn beneath
- leggingsForm-fitting leg garments
- fleeceWool still on sheep
- woolSheared animal fiber
henley · turtleneck · polypropylene · moisture-wicking · merino · midweight · heavyweight · cuffed
Reversal of position
- atmosphericOf the air above
- instabilityTendency toward unpredictable change
- heatingRaising temperature artificially
- diurnalActive during daylight
soaring
Rising effortlessly upward
- glidingEngineless aerial movement
- convectionHeat transfer via motion
- buoyancyFluid's upward resistance
lift · paragliding · hang-gliding · sailplane · circling · altitude · cumulus · hawk · vulture · kettle
long-johns
Insulating underwear for cold
wool · henley · turtleneck · polypropylene · moisture-wicking · merino · midweight · heavyweight · cuffed · layering
inversion
Reversal of position
- atmosphericOf the air above
- instabilityTendency toward unpredictable change
- heatingRaising temperature artificially
- convectionconvection, convection current, convection currents, convection cell, natural convection
- thermal underwearlong johns, union suit, waffle knit
- micrometeorologyboundary layer, turbulence, latent heat, energy balance, microclimate
- wintersnow, ice, cold, frozen, frost
- cold protectioninsulation, fur, blubber, feathers, down
- expedition gearbackpack, binoculars, compass, climbing rope, canteen
thermalsdowndrafts
Descending air currents
subsidence · microbursts · wind shear · downwash · turbulence
- thermal paperStock that darkens with heat
- thermal ventsSeafloor openings releasing heated water
- thermal bagInsulated carrying pouch
- thermal underwearInsulating garments worn beneath clothes
- thermal bathsHeated mineral water facilities
- thermal blanketsHeat-preserving emergency coverings