I’m Ian Worley. I’ve been flying since I was in high school.
I sold strawberries to get my pilot’s license. But I’m also
a teacher at the University of Vermont. I teach about the out of doors,
landscapes, living things and geology, and I teach about environmental
one of the things I do is I take my students on aerial field trips,
because we can see things from the sky that we can’t see so well
from the ground. But more excitingly, we can have a feel of
the sky and learn its shape, what’s going on in the air-- because
the air is sometime invisible and we can feel it with the airplane.
we’re off looking for thermals, those rising columns of air that
take gliders and hawks and butterflies to higher heights so they can
glide to the next thermal and find their way south during migration.”
traffic control clears the plane for take off…
can keep that shoulder harness loose and comfortable,” Dr. Worley
told me as we prepared to leave, “but make it nice and tight in
case we need to land in the trees.”
airborne, Dr. Worley searches for signs of a thermal...
see a little thermal possibility here, with a cloud above it to my left,
up over a swamp called Fairfield Swamp. So we’re going to fly
to it and see if we can get an upward rise of air, which we’ll
feel as a bump. And if it’s a really good bump we’ll feel
it in the seat of our pants.”
Just like that!
if that cloud were a thundercloud, if there were rain coming down and
lightening, we would be flying the opposite direction, not toward it,
away from the cloud, because those are rather violent things in the
sky and not good for an airplane of this kind.
this is a very benign cloud and to look at the cloud it’s cottony,
and because it’s looking like cotton--not cauliflower--that means
that it’s evaporating. So on the bottom new, moist air is being
added and on the top it’s evaporating, so this cloud is going
to stay about this size for awhile.
all the water that’s in a cloud that you see-- it’s water
--so it weighs something. So you can look at clouds and say, Huh, if
I weighed the water that I can see, I wonder how many elephants it would
be equal to. Well I’ve done some of that knowing what other people’s
research is, and we’re going to about a 50-80 elephant cloud up
ahead here. And if you’ve been watching this cloud you’ll
notice it’s evaporating, but another one to its left is forming.
See, now there’s our original cloud breaking up now, but off to
the left there’s a new one forming, and a couple others to the
Right ahead of us we have birds circling—hawks--between us and
the cloud. And that’s the best indication of a thermal.”
plane zips past 5-8 hawks that were rising in the thermal.
we just are going to go through it right now. And they were following
it and turned off to our right. And because we were flying at almost
100 mph and are not a glider, we were not able to join them. But if
we were in a glider, we could join that thermal and rise up with them.
They were in a stationary column that actually might be drifting a bit
because we do have the ever so slightest wind today, and the column
would drift with them.
sometimes the columns are not columns they are bubbles. They break free
from their source. We just had a little bump right here, it may not
show up in the camera but we can feel it in the airplane. So sometimes
a bubble of heated air goes up. And once that’s exhausted, there’s
no more rising air right there.
what we’re going to do is we’re going to fly under this
first cloud, and we’re already getting a little wiggly air up
here. This is not a day of high drama, so we may or may not have a noticeable
bump when we go under this cloud. But we’ll give it a try. And
then we’ll turn and go under the one to the left and see if that’s
an area of rising air.
definitely now the airplane is wiggling a little bit, so we’re
definitely in rising air…Here comes the cloud…and we are
kind of hopping around a little bit here. Looking at the cloud we don’t
notice it but looking at the horizon we notice it.
NO BIG DEAL of a thermal..
so we went under that and it was NO BIG DEAL of a thermal. And I’m
going to skinny around here and try this one that’s growing right
now, and see if we can find a bump.
now we’re definitely climbing. Right here it says we’re
going up at 500 feet a minute. Look at the altimeter, it’s moving
upward, and it says 600 feet a minute and we’ll probably come
out of this and well quit going up…and we’re back to stable
Through a Thermal
500 feet per minute...
back in stable air
it wasn’t a bump but it was certainly a stable climb. How many
feet did we go up? We went up for about 30 seconds at 500 feet/minute
so we went up about 250-300 feet as an airplane passing through it.
Now those hawks, the reason they were circling, was so they could stay
in it. And that’s what gliders do.
it looks like today if we are a bird or a butterfly or something else
that wants to take advantage of thermals, we’ll have light thermals
in the ground below us which is some open fields, some wooded cover,
and where the woods are it heats up more.
we’d be better off to go over near the ridges, because we definitely
see clouds over the ridges….”
off we flew, above Vermont’s tallest peak and beneath the cumulous
clouds, in search of a bumpy ride in a column of rising air…
to Dr. Ian Worley for the invitation to fly, for his colorful commentary
and his skillful flying, and especially for “watching for a safe
place to land” throughout the flight — but never needing it.