Weekend Argus (Saturday Edition)
Does anyone really know clouds at all?
WHEN CHARACTERS fly or fall through the sky in cartoons, they often eat, grab or even wear clouds as if the sky poofs were made of cotton balls. But what would it feel like to touch a cloud in real life?
Believe it or not, Nasa research scientist Kristina Pistone said, many of us have already touched a cloud – though we probably didn’t realise it at the time.
“Technically, clouds are really tiny, little droplets of water that happened to be floating in the air,” said Pistone. She works at the Bay Area Environmental Research Institute at the Nasa Ames Research Center in California.
Sound familiar? The definition applies to fog too. “If you’ve ever walked outside on a really foggy day where you can’t see very far, you’re walking through a cloud,” said Pistone. That’s because fog is just a type of cloud that forms on the ground.
If you don’t remember ever walking through fog, or perhaps live in a dry area where fog is not common, Pistone said it feels like walking through a very light drizzle.
“But not quite, because the cloud droplets are a lot smaller than the rain droplets that are part of drizzle,” she said.
Depending on a variety of factors, including how high it forms and how much water is in it, clouds come in a nearly endless variety. With a bit of practice, anyone can learn to recognise some of the more common varieties.
“The common ones that you’re going to see are cumulus. Those are the really puffy ones and they tend to be really low,” Pistone said. “And then there’s cirrus, which are the ones that are really, really high. And they’re wispy-looking. And those are actually ice clouds.”
Cloud colour is also interesting. Black or dark clouds usually mean a storm is coming because they're packed so full of water, that light can't pass through them. On the other hand, many clouds appear bright white because when light from the sun tries to shine through, it gets bounced around by the many suspended water droplets.
All of this is important for scientists to study because a lot of big, white clouds help reflect heat back into space. This means the kind and quantity of clouds on Earth can play a role in climate change.
And particles from sources such as pollution and smoke from forest fires may be able to affect how and why clouds form.
So, the next time you step outside and see a sky full of pillowy-white clouds, think about all the ways those tiny water droplets might be affecting the world around us – not only by delivering rain or snow, but by changing the planet’s temperature! |