[INTRO ♪] Over the years, we’ve talked about some
weird weather here on SciShow— from red sprites to thundersnow to spider
rain or murderous fogs. But all that still hardly scratches the surface
of how weird weather can get. From blood rain to volcanic tornadoes, here are five more kinds of weird, wacky,
wonderful and not-so-wonderful weather that happened
right here on Earth. Let’s start with a couple ways rain can
be… different from what we’re used to. In the Ancient Greek epic The Iliad, the god Zeus is said to have “showered bloody
raindrops on the earth.” And whether that was meant literally or not,
one thing is for sure: Sometimes, rain really is blood-red. Appropriately, it’s called blood rain. This phenomenon happens all over the world. And historically, some people thought it was
real, actual blood falling from the sky— which would be terrifying, but fortunately
it’s not true. Scientists have found that these rains are
usually stained either by dust from deserts or microscopic algae that
are suspended in the raindrops. A recent blood rain in Spain, for instance,
was tinted by the microalgae Haematococcus pluvialis, which releases a
red pigment when under stress. Of course, we’re still not quite sure how
algae get in the clouds. It’s probably from strong winds sweeping
over algal blooms, but we don’t know. Sometimes, though, the hypotheses are even
weirder. Like, in 2001, there was one specific blood
rain in southwest India that caused quite a bit of controversy. In it, scientists quickly found red-tinted
cells that looked like a certain kind of lichen or algae, but no one
could find any DNA. And no one could figure out how so much of
whatever it was got so high in the atmosphere. So they came up with a new hypothesis to explain
how the cells got there: They were alien. They’d hitched a ride on a meteor, then entered the atmosphere from above right
before India’s colorful rain. Some people even heard a loud boom before
the shower, like you’d get from a meteor hitting the
atmosphere. And further tests showed that the cells could
live through extremely high temperatures that kill most
terrestrial cells. So it wasn’t a totally silly proposal. Scientists have played around with the idea of life hitching rides on space rocks for decades. But as usual, it wasn’t aliens. In 2013—more than a decade after the event— scientists finally found the elusive DNA inside
the cells. Then, a couple years later, it was matched
with Trentepohlia annulata, an algae native to waters all over the world—though,
interestingly, not in India. It turned out that the cells’ membranes
were especially strong, which made the cells hearty in extreme environments and made it hard to find the DNA inside of them. We’re still not positive how so much of
it got lifted up into the air above southwestern India in 2001, but at least
we’re sure it isn’t aliens. Unless those aliens have been here for a really
long time. Now, Red rain can be troubling, but at least
it’s natural. Black rain, on the other hand, is pretty much
always our fault. Throughout the nineteenth and twentieth centuries, jet-black raindrops covered industrial centers, and it was pretty directly caused by burning coal. Coal actually stains water so effectively
that people living near coal plants around 1900 noticed that their rain was black
when the plants were running, and clearer when the plants were stopped. Coal releases lots of nasty stuff into the
atmosphere, including sulphur dioxide and nitrous oxides,
both major contributors to acid rain. But there’s also lots of soot that can get
high in the atmosphere. Then, it can get trapped in budding raindrops, only to fall as black rain that stains whatever
walls—and sheep—it touches. Seriously, there are accounts of poor little sheep
being dyed black by this. Today, there’s still some black rain in
China, but Clean Air Acts and other environmental
protections have mostly eliminated these coal-colored rains
from our skies. But humans have caused another type of black
rain, too. This one’s only been witnessed a few times— mostly in 1945 around Hiroshima and Nagasaki, cities in Japan where atomic bombs were dropped
at the end of World War II. Unlike what some of us might imagine, the bombs didn’t completely disintegrate
everything without a trace. That type of destruction only really happened
immediately around the drop zone. Outside that area, there were huge fires that
sent lots of carbon into the atmosphere— along with radioactive dust from the bombs themselves. Like with coal dust, the carbon and radioactive
fallout mixed with raindrops, only to fall as black, radioactive rain about
half an hour after the bombings. But thankfully, we haven’t seen any of that
for years. Now, there probably have been black rains
caused by ash and pumice from volcanic eruptions, but
it doesn’t happen very often. Usually, if rain is stained black, humans
are behind it. A black blizzard, though, isn’t actually a blizzard—
it’s an extreme dust storm. And fortunately, they haven’t happened since
the 1930s. Back then, the United States went through
what’s now famously called the Dust Bowl. Years of soil mismanagement in the Great Plains
had turned an extended drought even more devastating, leaving huge expanses of loose soil just sitting
on top of the ground. And when the wind whipped up, it lifted that dust
into gigantic clouds that could cover the entire sky, creating what became
known as “black blizzards”. The dust could block out the Sun hundreds
or thousands of kilometers away from the start of the storm, with the storm dropping
dust like a blizzard drops snow. Except the dust was a lot smaller than snow. It worked its way into people’s houses,
onto everything they owned, and then into their lungs. As a result, there was even a respiratory
condition that became known as “dust pneumonia”. One storm in May 1934 was almost three thousand
kilometers wide and swept more than 300 billion kilograms
of dust into the air. Chicago alone was covered in five million
kilograms of the stuff, and then the storm kept moving east until
it darkened the skies over cities throughout the East Coast. And then came Black Sunday: April 14, 1935. The cloud started in eastern Oklahoma and
picked up more and more dust as it raced southwest, pushed along by
65-kilometer-an-hour winds. The air was so filled with dust that day turned
to night wherever the storm went, and if you were inside, you could hardly see
a lightbulb in the center of your room. And that’s if you had a lightbulb. Most rural farms still didn’t have electricity,
and the much-dimmer candles they did have wouldn’t do anything to help
you see through the suffocating dust. Of course, the black blizzards of the 1930s
weren’t as bad as the planet-covering dust storms that the planet
Mars gets every couple years. But if the best thing you can say about the weather is, “Well, it’s worse on Mars,” it must
be pretty bad. Wait, volcanic tornadoes?! You’re kidding! That’s … that’s just not right. Just when you thought volcanoes were bad enough, it turns out they can get even weirder. When a volcano erupts, some of that super-hot
ash and rock climbs high into the atmosphere, but a lot
of it also travels down the side of the mountain as a gigantic, poisonous,
deadly avalanche. It’s called a pyroclastic flow. As the super-hot cloud moves along the ground, some of the gas trapped inside—including
a lot of sulphur dioxide—starts rising. As it rises, it starts spinning, because that’s
just sort of what air does as it rises. Everything has a little bit of sideways motion, so it’s really easy to get air columns spinning. And the rising hot air gets squashed together
by the air around it, which makes it spin faster and faster. It’s the same sort of effect that makes
a figure skater spin faster when they pull their arms in, only this time it’s a spinning column of
deadly poison. The faster the column spins, the more ash
and dust it can pull along with it— creating what looks like a mini-tornado. Thankfully, volcanic tornadoes are fairly rare, and they don’t seem to last too long or
go very far from their source. And, honestly, they’re not even real tornadoes. Actual tornadoes form through a completely
different process that involves giant air masses colliding with each other
over huge distances across the atmosphere. Volcanic tornadoes are more like dust devils, which are much smaller vortices that form
when some really hot ground warms the air immediately above it. Except in this case, it’s hot volcanic ash
heating the air instead. As a result, these events are officially known as “wind anomalies from thermal convection.” But come on—“Volcanic tornado” is a
way cooler name, even if it’s not quite precise. Now, depending on where you live,
you’re probably used to temperatures changing over the course of the day. You know how it goes: mornings are cooler,
it warms up by midday, it cools down again over the night, and then
the cycle more or less repeats. Sure, there are times when it gets warmer
all night or cooler all day, but even those special cases are nothing compared
to a heat burst. In a heat burst, the outside temperature can
climb by 5 or 10 degrees Celsius in as little as twenty minutes! Over the same period, the air just about completely
dries out, and the wind can gust at 130 kilometers an
hour. And all this happens in the middle of the night, when the weather thinks it can pull a fast
one on you. Heat bursts usually start with a thunderstorm. Thunderstorms tend to peter out as the night
goes on, when temperature differences across the atmosphere aren’t quite extreme enough to keep air
pockets violently convecting. But there can still be big pockets of hot
air, even as a thunderstorm dies down. Before a heat burst, moisture in the air hits
one of those hot, dry pockets and evaporates right then and there— turning back into water vapor long before
it ever reaches the ground. Evaporation steals energy from its surroundings, so the hot air starts to cool and fall toward
the ground, since cool air sinks. But air pressure is larger near the ground, and the increased pressure squeezes the
cool pocket as it falls and heats it back up again. As it heats up, it dries back out. So this same volume of air has gone from hot
and dry, to cool and damp, and back to hot and dry again—and that’s
when it finally hits the ground. Ground temperatures skyrocket, climbing as
much as ten or more degrees Celsius in anywhere from a couple hours
down to twenty minutes. And as the warm air pocket spreads out along
the ground, it also creates huge gusts of wind. And heat bursts aren’t super-rare like people
used to think; there are at least a dozen or so a year in
the midwestern United States alone. Thankfully, though, they aren’t typically as dangerous as other things that can happen during storms, like
huge hail or tornadoes. So, if you’re cozy in bed and the temperature
shoots up suddenly, I guess you can take comfort knowing that your cat is probably not playing with your
thermostat. These five pieces of extreme weather are flat-out
bizarre, and it feels like they shouldn’t even be
allowed. But somehow, they still don’t even really scratch
the surface of all the weird things that happen in our
atmosphere. And don’t even get me started on the kinds
of otherworldly weather that happen on some of the exoplanets we’ve
discovered. Because unlike the algae in blood rain, that
stuff really is alien. If you want to learn more about them, we have an episode over on SciShow Space all
about it! [OUTRO ♪]
