Science For Six-Year-Olds: Noctilucent Clouds

Science For Six-Year-Olds is a recurring segment on Science Decoded for Mrs. Podolak's first grade class at Lincoln-Hubbard elementary school. This year in first grade we've also done an experiment with butter, talked about hurricanes, sugar maple trees, and learned a song about the states of matter.
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Hello First Graders! Now that it is officially Spring, it seems like a great time to start your new science unit on clouds. I hear you have started to learn about what clouds are made of, and the different types of clouds. I wanted to share some information with you about a special type of cloud called a Noctilucent cloud. Have any of you ever heard of a Noctilucent cloud? They are a unique type of cloud that can be observed at night and are formed by ice at the line where Earth's atmosphere meets space. These clouds are known for looking shiny because they are so high up in the atmosphere that they stay lit up by the sun, even after it has set for the day.

Noctilucent clouds. Image via NASA

This kind of cloud is a relatively new discovery. They were first observed in 1885, which is a long time ago but not for scientists who have been observing and learning about the Earth for as long as humans have existed. Since they began studying Noctilucent clouds, scientists have learned that they form at temperatures around -230°F. What is the temperature outside today? What about in your classroom? Can you imagine how cold it is at -230°F? In the upper atmosphere when it is that cold, dust blowing up from Earth below or falling down into the atmosphere from space gives water vapor a place to condense and freeze. 

Noctilucent clouds are most visible as the sun is going down or right after it has set, typically in Summer months between 50° and 70° north and south of the equator. Can you find where that is on a globe? Lately these clouds have been appearing outside of their normal range and with increased frequency. This has led some researchers to hypothesize (propose an explanation based on the preliminary evidence) that the appearance of these clouds may be linked in some way to global climate change. 

Global warming is causing the atmosphere to heat up, and when it heats up it expands. Noctilucent clouds form at the edge of the atmosphere, if the atmosphere is pushed out further it will be colder (because it is very cold out in space). If it is colder, it is possible that this would result in more Noctilucent clouds forming and forming in different areas. However, this is just one possible explanation scientists still have a lot of research to do to learn more about these special clouds and figure out exactly why they are increasing in prevalence. 

Check out this great video of Noctilucent clouds captured from onboard the International Space Station. If you have any questions let me know and I'll do my best to answer them, but remember scientists are still learning about these clouds and there may not be answers yet. 

*I got the idea for this post when this Wired article popped up in a Google search about clouds. For more information about Noctilucent clouds in general, NASA also has some great information (though not specifically for kids.)

Knut the Polar Bear Dead At Age Four

Knut as a baby. Source: Wikimedia Commons

Yes, I am posting a memorial piece for a polar bear. Yes, I know that I talk about polar bears too much. But, this really is an interesting case of mysterious death - one that was witnessed by hundreds and has cause an onslaught of media coverage of what may very well be history's most widely read polar bear obituary.

Knut was a polar bear born in captivity in the Berlin Zoo in December of 2006. He gained world wide fame, basically for being so darn cute. He was raised by the zookeepers after being rejected by his mother and was the first polar bear to survive infancy at the Berlin Zoo in 30 years. He died March 19, 2011 in his enclosure at the zoo in front of an estimated 700 viewers. His death has been the subject of worldwide media coverage from the UK's Daily Mail to New York Magazine.

Reports say that the polar bear had a spasm, and was then seen floating in the water in the enclosure before the exhibit was closed off by zoo personnel. Polar bears in captivity have been known to live up to 30 years, and Knut was not known to have any medical problems so his sudden death at age four is mysterious. A necropsy (an autopsy for animals) will be performed to determine what happened to the bear.

Knut a little older. Source: Wikimedia Commons

As far as polar bears go, you couldn't have a bigger celebrity than Knut. He was on the cover of Vanity Fair in 2007, he has been marketed through plush toys and children's books, he was the subject documentary films and even had his name trademarked by the Berlin Zoo. His untimely death even warranted him an obituary in People Magazine's website.

While I don't intend to get sappy about the loss of this animal, I do think it is important to note because Knut succeeded in getting people to feel emotionally invested in animal rights issues and to get people talking about science topics like climate change (and its effects on polar bears). He was a major draw to the Berlin Zoo and the loss of revenue will most certainly be felt. Hopefully the necropsy will be able to determine how he died so that zookeepers can learn something about how to keep animals in captivity healthy.

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Update 4/1/11 - The Berlin Zoo has released the results of Knut's necropsy. The findings show that the polar bear's official cause of death is drowning, which occurred when he collapsed into the pool in his enclosure. The reason Knut collapsed is still a bit of a mystery. The necropsy showed encephalitis (brain swelling and irritation) most likely caused by a virus, although the exact virus remains to be identified. So far rabies, botulism, and bovine spongiform encephalopathy (mad cow disease) have been definitively ruled out as the cause of the brain swelling. The zoo will continue to test Knut's remains to try to identify the virus.

Bubble Tip Anemone

The picture of the day on Wikipedia Commons was science related so I thought I'd re-post it. It is the Entacmaea quadricolor, also known as the Bubble Tip Anemone.

Sea Anemones

There is no real point to publishing this image other than that I just think it is cool and very pretty. It was on Wikipedia Commons as the picture of the day, which is how I found it. (Side note: has it become obvious yet how much I love Wikimedia Commons?)

This image is from the book The Royal Natural History by Richard Lydekker, which dates back to 1893.

Fractals

Benoit Mandelbrot, the mathematician who discovered fractals, died recently. While its true that I don't really like math - I do love fractals. It probably has to do with the fact that they are such an amazing natural phenomenon. Francis was explaining fractals to me in terms of geology recently, but the main idea is that some things in nature (rocks, vegetables, etc) have an essential structure that always remains the same. So, it will be the same shape no matter how many times it is divided. Probably one of the most well known fractals is cauliflower - try breaking it apart into little pieces and you will see what I mean, it always looks the same, even when its really small.


From the BBC:
Fractal mathematician Benoit Mandelbrot dies aged 85
Pictures of Fractals