A buzzard, a seagull, an eagle or any other soaring bird gains altitude by ... well, soaring and that is only possible when there are rising thermal parcels of rising air. But then, when does it happen?
Well, I own and fly often a light aircraft, in all kinds of weather and I can tell you this:
Thermals are most efficient when the sun shines and warm air lifts, then cools down by adiabatic effect, forming cumulus clouds under which you can be sure to meet buzzards and ... glider pilots.
Those can be very powerful. I once fly a glider with my son and we were caught under a cumulus and moved into it, loosing sight. My son then got the air brakes out, even the landing gear and side-slipped, trying to come down without exceeding maximum speed. And this is why glider pilots wear a parachute; to bail out if they can't get out of the thermal. Luckily we did it without bailing out. But I digress.
When are thermals the most effective? Well when the sun shines over something hard and dark, like a large parking lot. A bit less over a dark forest and even less over a wheat field, to not at all over a lake or the sea.
How about overcast then? Well, it depends how much overcast it is. A thick cumulonimbus won't let enough light in to warm up the ground to some extend. But it is difficult to tell. Sometimes I even feel thermals during the Norwegian winter, when flying from a snow covered white field to a dark forest. I have been flying for ten years now, about one hundred hours per year and I am never sure what to expect up there. The sky is always full of surprises but birds are born to read it and they can do it so much better than us.
Well, I own and fly often a light aircraft, in all kinds of weather and I can tell you this:
Thermals are most efficient when the sun shines and warm air lifts, then cools down by adiabatic effect, forming cumulus clouds under which you can be sure to meet buzzards and ... glider pilots.
Those can be very powerful. I once fly a glider with my son and we were caught under a cumulus and moved into it, loosing sight. My son then got the air brakes out, even the landing gear and side-slipped, trying to come down without exceeding maximum speed. And this is why glider pilots wear a parachute; to bail out if they can't get out of the thermal. Luckily we did it without bailing out. But I digress.
When are thermals the most effective? Well when the sun shines over something hard and dark, like a large parking lot. A bit less over a dark forest and even less over a wheat field, to not at all over a lake or the sea.
How about overcast then? Well, it depends how much overcast it is. A thick cumulonimbus won't let enough light in to warm up the ground to some extend. But it is difficult to tell. Sometimes I even feel thermals during the Norwegian winter, when flying from a snow covered white field to a dark forest. I have been flying for ten years now, about one hundred hours per year and I am never sure what to expect up there. The sky is always full of surprises but birds are born to read it and they can do it so much better than us.
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Usually. Even though there aren't as many thermals as on a sunny day they're still around and buzzards can still find them.
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They use thermals. The thermals are there, whether it's clear skies or overcast. It's a matter of finding them.
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yes