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Text, Viewspace. The show will continue in 15 seconds. Coming up: Look down on Earth's clouds with NASA satellites.
The timer at top right counts down from 15 seconds.
The text appears on a background of stars which move slowly towards and past us.

Planet Earth against the blackness of space. 
Text, Our sapphire-blue world has 331 million cubic miles of water. 
3/4 of Earth cut in the form of a pie chart. 
Text, Water covers about 75% of Earth's surface. 
Almost all of Earth's water — about 98% — is liquid, and about 2% is stored as ice and snow. 
Earth with the continents Europe and Africa surrounded by blue water, and an area of white at the North Pole. 
Text, Our atmosphere holds only 0.001 of 1% of Earth's water. 
A very small fraction of that condenses to form clouds. But it has an enormous effect on our lives. 
Clouds high in the sky range in size and shape, from wispy to fluffy. 
On the surface of Earth, clouds move in spiral motions in various directions. 
Text, Clouds influence weather and climate. 
Clouds carry water from one region of the planet to another. 
Clouds also regulate Earth's temperature by absorbing and reflecting sunlight, and by trapping heat.

Planet slowly rotates in galaxy full of colorful specks against the blackness of space. 
Text, at-a-GLANCE, CLOUDS. 
There are many different types of clouds. 
Several clouds of various shapes and sizes in a blue sky appear. 
Text, Clouds are classified by their shape and their altitude, or height above Earth's surface. 
Three layers of clouds labeled Low, Middle, and High. Low Clouds, Nimbostratus -- Stratocumulus, Stratus -- and Cumulus. Middle Clouds, Altostratus and Altocumulus. High Clouds, Cirrostratus -- Cirrus, Cirrocumulus, and Cumulonimbus. 
High Clouds. Cirrus -- Wispy feather-like clouds called cirrus appear high in the atmosphere. 
Layer of thin clouds over green land. 
Text, They are made of ice crystals and typically are thin and wispy. 
Cirrus clouds often reveal the direction of air movement at their altitude. 
A sky full of thick white clouds surround a volcano. 
Text, Low Clouds. Stratus -- Stratus clouds form in layers, and they can cover the entire sky like a blanket. 
Their bases can be just a few hundred feet above the ground. 
When stratus clouds form at ground level, they are called fog. 
Bright green land beside a body of blue water with a stretch of clouds above. 
Small patches of clouds throughout the sky. 
Text, Low Clouds. Cumulus -- Cumulus clouds have a flat base with rounded fluffy tops. 
Their heights depend on temperature differences between the rising and surrounding air. 
A large circular cloud in the shape of a disc. 
Cumulus clouds can develop into towering cumulonimbus clouds, which sometimes rise to more than 50,000 feet. 
When rising air reaches the bottom of the stratosphere—the second layer of the Earth's atmosphere—it is deflected by a warm layer of air and spreads the cloud outward, forming an anvil shape.

A blue hexagon appears in the middle of a gray background split into two halves by a line. A banner is outlined in light blue for the title, Myth vs Reality. An illustration with sea serpents surrounding a ship is above Myth. A satellite view of rippled clouds is above reality. A dark, rotating planet floats in the background at the bottom. The Myth side is highlighted. Text, Clouds overhead means a cool day below.
The reality side is highlighted. Text, Not all clouds cool Earth's surface, and atmosphere. High, thin cirrus clouds actually have a warming effect. They not only let the majority of the Sun's warming rays pass through, but they also trap heat that would normally escape to space.

Thick clouds cover a valley.
Text, Valley Fog, British Columbia.
Low-lying, layered, stratus clouds that form at ground level are called fog.
Moving down the foggy mountains into the valley.
Text, In the Pacific Northwest, valley fog forms when cold air sinks into a valley.
Looking down on land edged with green and branched white in the center.
Text, Moist air in the valley gets chilled and water vapor condenses into fog droplets.
A thick patch of white is labeled "fog."
Text, When fog becomes thick enough, it reflects a large amount of sunlight back into space.
Water tributaries branch into the land.
Text, These low-lying stratus clouds also allow some of Earth's heat to escape to space.
Text, This cools the surface.

Clouds roll through the sky. Text, Clouds, Hot & Cold
White puffy clouds in a blue sky. Text, Stand in the shadow of a big, fluffy cumulus cloud on a sunny summer's day and you can feel the change in temperature.
Clouds above a green field, Text, The clouds block most of the Sun's radiation from reaching the ground, making it feel cooler when you stand underneath it.
Not all clouds cool Earth's surface, though.
Yellow dots drop from the sun. When they hit the ground, they bounce up as red dots. Text, High thin cirrus clouds let sunlight pass through to the surface, but then trap most heat coming from the surface. This gradually warms Earth.
The red dots bounce off a cloud and return to Earth.
Big puffy cumulus clouds neither warm nor cool Earth's surface significantly.
Yellow dots from the sun bounce upward when they reach the clouds. Text, Thick cumulus clouds reflect the Sun's energy back into space.
Red dots rise from the ground. Text, But cumulus clouds also act like a thick blanket insulating Earth's surface. They keep heat in.
Low stratus clouds cool Earth.
Yellow dots from the sun bounce upward when they reach the clouds. Text, They reflect most of the Sun's energy back to space.
Red dots rise through the clouds. Text, In addition, stratus clouds allow some of the Earth's heat to escape to space.
NASA's Aqua satellite reveals how clouds both reflect and trap heat.
Blue, green and white areas on a graphic of Earth. A scale depicts Reflectivity from Least to Most. Text, Some Clouds Reflect Sunlight. Dark blue, cloudless ocean regions reflect the least amount of sunlight back to space.
Bright clouds in snow-covered surfaces reflect the greatest amounts of sunlight back to space.
Red, bluish-purple, white and yellow areas on a graphic of Earth. A scale depicts Trapped Heat from Least to Most. Text, Some Clouds Trap Heat. This image shows where heat is escaping and where it is trapped.
Cloudless, warm, yellow-colored regions trap the least amount of heat.
High cold clouds in blue and white trap the most amount of heat.
Clouds below an airplane wing. Text, Every day thousands of planes take off and land around the world.
2002 NASA Image, Rhone Valley Eastern France. The exhaust from these planes creates contrails: human-made cirrus clouds.
Because cirrus clouds allow some light to pass through to the surface but trap heat trying to escape, contrails can increase surface temperatures.
2004 NASA Image Southeastern U.S. In the United States, the number of cirrus clouds increased by 1% per decade.
Some scientists think this is due to the increase in air traffic and contrails.
Thick clouds reflect pink in a blue sky. Text, Clouds have long held our imaginations and curiosity.
A vertical cloud. Text, We imagine familiar objects or animals in their shapes...
Satellite image of a hurricane. Text, and fear their great power in large storms.
But clouds do more than pique our interest.
Cloud formations shift across the Earth.Text, They play a significant role in our everyday lives by regulating Earth's temperatures, making our world a comfortable place to live.

A blue hexagon appears in the middle of a gray background split into two halves by a line. A banner is outlined in light blue for the title, Myth vs Reality. An illustration with sea serpents surrounding a ship is above Myth. A satellite view of rippled clouds is above reality. A dark, rotating planet floats in the background at the bottom. The Myth side is highlighted. Text, Clouds do not affect Earth's air temperature.
The reality side is highlighted. Text, Clouds regulate temperatures on Earth by reflecting sunlight and by preventing Earth's heat from escaping to space.

Text, Noctilucent Clouds, Northern Europe. A rare phenomenon, noctilucent or "night-shining" clouds appear only in the summertime.
They are made of water-ice crystals that probably formed on meteoric dust.
They look like cirrus clouds, but they form at much higher altitudes and only a very cold temperatures.
They are so high up that the Sun can still illuminate them even after it has set.
Noctilucent Clouds, Antarctica, December 2009, NASA AIM Satellite Image. Since its launch in 2007, NASA's AIM satellite has discovered that the number of noctilucent clouds has increased over the Arctic and Antarctic.
Noctilucent Clouds, Northern Europe. Because they are so sensitive to temperatures in the atmosphere, noctilucent clouds can provide information about the temperature and other characteristics in their lofty region of the atmosphere.

Text, Ship Tracks, Northeastern Pacific Ocean. 
Ship tracks streak across the skies of the northeastern Pacific Ocean. 
A map of the world with a red dot on the northern Pacific Ocean. 
Several bands of thin white clouds run in parallel to each other. 
Text, These clouds form around tiny particles created in a ship's exhaust. 
Image zooms out and down to show how the ship track clouds appear in layers 
Text, The ship tracks are brighter than the natural unpolluted clouds. 
Image continues to zoom outward, with the Earth's horizon in the distance. 
NASA's Terra satellite has shown that ship tracks have smaller -- and many more -- water droplets than other marine clouds. 
Clouds with a higher quantity of smaller water droplets reflect more sunlight, making them appear brighter and reducing the amount of sunlight reaching the surface.