Paraglider Thermalling.

 

As a paraglider pilot, the long term goal is to progress to cross country flying. Cross country flights are achieved by finding and using thermals to gain height and continue the flight.

Thermals are an invisible column of rising air. These can sometimes be very powerful, fast and turbulent. Warm air tends to rise, so when a patch of air is heated, it rises through the cooler surrounding air resulting in a thermal column or bubble. Altitude is gained effectively by a paraglider by riding one of these "invisible elevators". This needs to be managed in such a way that we enter a new thermal long before we get close to the ground.

Thermic activity usually gets stronger at higher altitude than close to the ground. This continues until the thermal temperature equals or is lower than surrounding air when is starts o weaken and stop. It is therefore easier to catch a thermal half way to a cloud than it is near the ground. The good pilot has great observation skills to find the source and result of thermic activity. Thermals are generated from different sources depending on the angle of the sun relativeto these sources.

A hillside facing the late morning sunshine should produce moderate to good thermals. Later that same day the same hill face without the effects of the sun on it will be producing the opposite effect - sinking air, while the face on the other side of the same hill now facing the sun will be producing thermic flow. This is the principal idea which now needs to be applied to many other possible thermal generating poits on the landscape.

Here is a list of some effective sources of thermic activity.

1. Hillsides or mountain sides in the sun.

2. Rocky outcrops in otherwise vegetated landscape(these take time to heat up so they work later in the afternoon)

3. A well known source to the pro's are tar roads. These get very hot and produce consistent hot air.

4. Houses and villages(especially dark roofs and clusters of buildings)

5. Large lighter often drier grassy patches amongst darker green vegetation can be useful, however we cannot neglect to mention the very dark dried cotton fields that produce a powerful bumpy ride.

6. The ridgeline of a hill or mountain is very often a good source after lunch time through to the evening.

7. Trees,shrubs and thick vegetation provide late afternoon thermals.

8. And then theres so called "magic lift" which is more difficult to explain. Terrain and specific wind conditions where opposing breezes collide and are forced upwards can create the magic.

Remember that thermals need a heat source and a trigger to “drip from”. Some sources offer both functions while others such as a field of dry grass, needs a trigger point such as an adjacent line of trees, a tractor moving across it and so on. In the appropriate conditions, thermals result in clouds, making them much easier to spot at altitude, but not all clouds have active thermals.

When we have found and entered a thermal, the next black art is to stay in it.