Tip:
Highlight text to annotate it
X
[ music ]
The mysterious rumble of Thundersnow, presented by
Science at NASA.
A snow storm is usually a silent thing.
Snowflakes drift down soundlessly from the sky, landing
softly on a blanket of white cushioned ground.
That's why a freak snow storm that hit Alabama last month
was so surprising.
It was downright noisy.
As bolts of purple lightning crackled through snowy clouds
above, waves of rumbling thunder woke people up and drew
them outside in slippers and housecoats to see
what was happening.
One of those people was NASA, Earth Scientist,
Walt Petersen.
"It was a rare phenomenon called Thundersnow" he says.
"And it rolled right over our research station, at the
National Space Science and Technology Center,
in Huntsville, Alabama."
Petersen and colleagues monitored the thunder snowstorm as
it raged overhead.
They used radars, lightning detectors, and other
instruments to probe what was happening inside the tempest.
It turns out that deep inside the storm, snowflakes were
forming with a mixture of different sizes.
Strong, windy updrafts caused them to bump and rub
together and exchange electric charge.
Think of socks rubbing on carpet - it's pretty much the
same phenomenon.
Soon the storm was so charged up that the lightning began
to crackle, heralding the fall of snow, with a loud rumble
of thunder. [ thunder rumbles ]
"We got a lot of data," says Petersen.
"When we finish analyzing it all, we'll have a much better
idea what causes unusual storms like this."
Indeed, snow in Alabama is rare, and noisy snow is just
unheard of.
"Actually," says Petersen, "we heard it loud and clear."
[ thunder rumbles ]
For more information about Thundersnow and other NASA,
Earth Science research, please visit science.nasa.gov.