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[dramatic percussion music]

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- HEY, THERE, AND WELCOME
TO "NASA LAUNCHPAD."

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I'M JUSTIN TULLY.

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CLOUDS: WE'VE ALL SEEN THEM,

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A SEEMINGLY NORMAL PART
OF THIS PLANET WE CALL EARTH.

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BUT HAVE YOU EVER SEEN
A BLUE CLOUD?

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OR WHAT ABOUT ONE
THAT LOOKS LIKE IT'S GLOWING?

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NO?

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WELL, I CAN ASSURE YOU
THAT THEY DO EXIST,

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AND SCIENTISTS
ARE VERY INTERESTED

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IN THESE SPECIAL CLOUDS.

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KNOWN AS NOCTILUCENT,
OR NIGHT-SHINING, CLOUDS,

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THESE HIGH-IN-THE-SKY BRETHREN
OF EVERYDAY CLOUDS

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ARE ACTUALLY MORE COMMON
THAN YOU MIGHT THINK.

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FIRST DISCOVERED IN 1885,
MANY SCIENTISTS

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HAVE BEEN INTRIGUED
BY THESE SHINY CLOUDS FOR YEARS

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BUT HAD VERY LITTLE IN THE WAY
OF TECHNOLOGY TO STUDY THEM.

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HOWEVER, BECAUSE OF ADVANCES
IN SCIENCE,

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SCIENTISTS ARE LEARNING
A LOT MORE

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ABOUT NOCTILUCENT CLOUDS.

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THESE GLOWING CLOUDS
ARE A BIT DIFFERENT

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THAN THE CLOUDS
WE'RE ALL USED TO.

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YOU CAN SEE REGULAR CLOUDS
VIRTUALLY ANYWHERE ON EARTH,

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BUT YOU CAN ONLY SEE
NOCTILUCENT CLOUDS

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AT AROUND 55 DEGREES LATITUDE
OR HIGHER.

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YOU'RE WATCHING
A TIME-LAPSE VIDEO

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OF THESE BEAUTIFUL
NIGHT-SHINING CLOUDS.

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IT'S PRETTY NEAT.

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REGULAR CLOUDS ARE FOUND
FROM GROUND LEVEL--

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WE CALL THOSE CLOUDS FOG--
TO ABOUT 9 KILOMETERS,

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OR ROUGHLY 6 MILES,
IN THE SKY,

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WHEREAS NOCTILUCENT CLOUDS
ARE FOUND

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AT A WHOPPING 83 KILOMETERS,
OR 50 MILES, ABOVE THE SURFACE.

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THAT'S IN THE VERY UPPER LIMITS
OF OUR ATMOSPHERE,

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RIGHT ON THE EDGE OF SPACE,
LITERALLY.

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AND UNLIKE NORMAL CLOUDS,

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NOCTILUCENT CLOUDS
ARE ONLY VISIBLE

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IN WHATEVER HEMISPHERE
IS EXPERIENCING SUMMER.

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BECAUSE THESE CLOUDS
ARE SO HIGH UP,

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IT MAKES THEM
REALLY TOUGH TO SEE.

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THE OPTIMAL VIEWING TIME
FOR NOCTILUCENT CLOUDS

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IS RIGHT BEFORE THE SUNRISE
OR RIGHT AFTER SUNSET.

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THIS IS BECAUSE
NOCTILUCENT CLOUDS

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ARE HIGH ENOUGH
IN OUR ATMOSPHERE

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TO STILL BE ILLUMINATED
BY THE SUN,

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WHILE NORMAL LOW-FLYING CLOUDS
ARE NOT.

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OKAY, SO BEFORE WE GET
FURTHER INTO THIS,

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LET'S GO OVER THE THREE THINGS
YOU NEED TO MAKE A CLOUD.

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IT'S ACTUALLY VERY SIMPLE.

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YOU NEED TEMPERATURES
BELOW THE FROST POINT,

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WATER VAPOR,

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AND A NUCLEATION SITE,
LIKE A PARTICLE,

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SOMETHING FOR THE WATER VAPOR
TO GRAB ON TO.

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SO WHEN THE WATER VAPOR
COMES INTO CONTACT

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WITH A HIGH-ALTITUDE PARTICLE,

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THE VAPOR BEGINS TO FORM A MASS
AROUND THE PARTICLE,

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MAKING IT THE CENTER,
OR NUCLEATION SITE.

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AND AS MORE AND MORE WATER
ATTACHES TO THE PARTICLE,

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IT SLOWLY BECOMES VISIBLE,
AND POOF,

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YOU'VE GOT YOURSELF A CLOUD.

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IN ORDER TO STUDY THESE
NIGHT-SHINING CLOUDS BETTER,

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SCIENTISTS NEEDED
TO GET A CLOSER LOOK AT THEM,

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SO THEY WORKED TOGETHER
WITH ENGINEERS

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TO LAUNCH THE AERONOMY OF ICE
IN THE MESOSPHERE MISSION,

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OR AIM.

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YEAH, YOU HEARD ME:
MESOSPHERE.

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YOU KNOW?
YOU DON'T KNOW?

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OKAY.

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REMEMBER THAT SCIENTISTS
DIVIDE EARTH'S ATMOSPHERE

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INTO FOUR LAYERS.

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THE ATMOSPHERE IS THICKEST,
OR MORE DENSE, NEAR THE SURFACE

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AND THINS OUT
THE HIGHER YOU GO

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UNTIL IT EVENTUALLY MERGES
WITH SPACE.

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TROPOSPHERE IS THE FIRST LAYER
JUST ABOVE EARTH'S SURFACE.

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ALTHOUGH IT'S NOT VERY HIGH,
ONLY ABOUT 12 TO 16 KILOMETERS,

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ABOUT HALF OF OUR ATMOSPHERE
IS IN THIS LAYER,

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AND THIS
IS WHERE WEATHER OCCURS.

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THE STRATOSPHERE IS NEXT.

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IT'S ALSO
A PRETTY STABLE LAYER,

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AND THIS IS WHERE YOU'LL SEE
MOST JET AIRCRAFT FLYING.

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THE OZONE LAYER, FOUND HERE,

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ABSORBS MOST OF THE HARMFUL RAYS
FROM THE SUN,

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PROTECTING US ON EARTH.

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NEXT LAYER: THE MESOSPHERE.

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THIS IS THE LAYER
THAT IS HOME

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TO THESE BEAUTIFUL
NOCTILUCENT CLOUDS

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AND THE PART OF THE ATMOSPHERE

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WHERE METEORS OR ROCK FRAGMENTS
BURN UP.

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THE THERMOSPHERE IS THE WIDEST
BAND OF OUR ATMOSPHERE,

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STRETCHING OUT ALMOST
300 KILOMETERS ABOVE EARTH.

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HERE YOU'LL FIND
THOSE AWESOME AURORAS,

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AND THIS IS WHERE THE
SPACE SHUTTLE ACTUALLY FLIES.

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THE ATMOSPHERE HERE IS VERY THIN
AS IT MERGES INTO THE EXOSPHERE.

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THIS IS THE BOUNDARY AREA

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WHERE THE ATMOSPHERE ENDS
AND SPACE BEGINS.

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SO YOU CAN SEE
WHY SCIENTISTS

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MIGHT NEED A SPECIAL KIND
OF SATELLITE

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TO HELP GATHER DATA
ABOUT THESE INTERESTING CLOUDS

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FOUND KILOMETERS
ABOVE ORDINARY CLOUDS.

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BUT INSTEAD OF ME TELLING YOU
ABOUT NOCTILUCENT CLOUDS,

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I'M GOING TO REFER YOU
TO AN EXPERT ON THE SUBJECT.

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DR. JAMES RUSSELL
IS THE PRINCIPAL INVESTIGATOR

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FOR THE AIM MISSION

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AND RECENTLY MET UP
WITH OUR CAMERAS

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TO SHED SOME LIGHT
ON THESE PECULIAR CLOUDS

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AND FILL US IN ON SOME
OF THE THINGS WE'VE LEARNED

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THANKS TO THE AIM MISSION.

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- FIRST OFF, WE NOW SEE
THAT THESE CLOUDS

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ARE MUCH BRIGHTER
THAN WHAT WE THOUGHT,

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BECAUSE NOW WE HAVE
MUCH HIGHER-RESOLUTION DATA.

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SPATIALLY, WE CAN SEE
THE BRIGHTNESS OF THE CLOUDS.

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WHEN YOU LOOK AT THESE CLOUDS
AND YOU SEE THEM VISIBLY,

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WHAT YOU'RE LOOKING AT
IS THE CLOUDS

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IN A VERY NARROW LAYER,

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ABOUT 3 KILOMETERS,
OR 2 MILES, IN THICKNESS.

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BUT WHEN YOU--
NOW WHAT WE KNOW IS, FROM AIM,

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THAT THEY REALLY EXIST
OVER A RANGE

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OF ABOUT SEVEN MILES
IN THICKNESS.

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- HOW ABOUT THAT?

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AIM HAS ALSO HELPED
TO ANSWER THE QUESTION,

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"JUST HOW DO THESE CLOUDS FORM
SO HIGH IN OUR ATMOSPHERE?"

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THE ANSWER, DR. RUSSELL?

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- AND THERE WERE THREE MAIN
THEORIES FOR THESE PARTICLES.

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ONE WAS COSMIC SMOKE,

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WHICH IS MICROMETEORITES
COMING INTO THE ATMOSPHERE,

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AND THE MICROMETEORITES
THEN BURN UP,

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AND WHAT'S LEFT OVER ARE THESE
VERY TINY SMOKE PARTICLES

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A NANOMETER IN SIZE,
ABOUT THE SIZE OF A HUMAN HAIR.

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WELL, WHAT AIM HAS SHOWN NOW
IS THAT THE COSMIC SMOKE,

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WHICH WE'RE MEASURING
WITH THE AIM INSTRUMENT,

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IS A DOMINANT SOURCE
OF NUCLEATION PARTICLES

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FOR THE WATER TO CONDENSE ON
AND GROW.

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- SO THE CLOUDS ARE MADE
FROM SMALL PIECES OF METEORS,

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OR MICROMETEORS.

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PRETTY COOL.

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THESE CLOUDS WERE ONCE ONLY SEEN
IN POLAR REGIONS,

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BUT IN RECENT YEARS,

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THERE HAVE BEEN
MORE CLOUDS THAN EVER,

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AND THEY'VE BEEN
MAKING THEIR WAY

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TO MORE PARTS OF OUR PLANET.

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SO WHY?

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THERE COULD BE
A FEW EXPLANATIONS,

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BUT THE MAJOR THEORY
ON WHY THIS IS HAPPENING

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HAS TO DO WITH A SUBJECT

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YOU'VE PROBABLY BEEN HEARING
A LOT ABOUT LATELY:

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CLIMATE CHANGE.

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- WE THINK
THERE IS A CONNECTION,

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AND THE CONNECTION IS SOMETHING
THAT YOU MIGHT NOT THINK ABOUT.

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THE REASON WE HAVE
GLOBAL WARMING DOWN LOW

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IS BECAUSE CO2 BUILDS UP
IN THE ATMOSPHERE.

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THAT'S THE MAIN REASON FOR IT.

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WHEN WE BURN FOSSIL FUELS,
CO2 BUILDS UP,

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AND CO2 ACTS LIKE A BLANKET,
A THICK BLANKET,

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AND SO IT ABSORBS HEAT
FROM THE EARTH

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AND RERADIATES IT
BACK TO THE EARTH

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AND MAKES THE ATMOSPHERE WARM.

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BUT UP HIGH
WHERE THE CLOUDS ARE,

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ON THE EDGE OF SPACE,

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THE BLANKET IS VERY THIN,

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SO CO2 BUILDUP THERE
ACTUALLY CAUSES YOU TO LOSE HEAT

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AND MAKES THE ATMOSPHERE COOL.

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SO WITH CO2 BUILDUP
OVER A LONG TIME,

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THEN THE ATMOSPHERE CAN COOL--

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AND WE'VE SHOWN WITH MODELS
THAT THIS INDEED CAN HAPPEN--

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AND COOLING ATMOSPHERE

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MAKES CONDITIONS MORE FAVORABLE
FOR FORMING CLOUDS,

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BECAUSE YOU GOT TO HAVE
COLD TEMPERATURES.

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AND IF THEY STAY COLDER LONGER

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AND IF THAT COLDNESS
GOES TO LOWER LATITUDES

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THAN WHAT IT HAS IN THE PAST,

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THEN YOU'LL START TO SEE
MORE CLOUDS

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AND OVER A BROADER
LATITUDE RANGE

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THAN WHAT YOU WOULD

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IF THE ATMOSPHERE
WERE NOT COLDER.

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- SO WHAT'S GOING ON HERE?

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WELL, OUR PLANET IS CHANGING,

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AND THANKS TO SCIENTISTS
LIKE DR. RUSSELL,

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WE'RE ABLE TO UNDERSTAND

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A LITTLE MORE
OF WHAT'S HAPPENING.

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SO THE NEXT TIME YOU FIND
YOURSELF AT A HIGH LATITUDE,

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SOMETIME IN SUMMER
RIGHT AFTER A SUNSET,

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LOOK UP, AND REMEMBER,

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SOME CLOUDS REALLY DO
HAVE A SILVER LINING--

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OR AT LEAST
THEY LOOK LIKE THEY DO.

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THANKS FOR WATCHING
"NASA LAUNCHPAD."

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UNTIL NEXT TIME,
I'M JUSTIN TULLY.