Curious Kids: where do clouds come from and why do they have different shapes?



File 20180912 181254 s09p4f.jpg?ixlib=rb 1.1
Sometimes air goes up past the condensation level then falls back below the condensation level, then up, then below, again and again. This creates clouds that are stripy, often with lines between the clouds.
Robert Lawry/Author provided, Author provided

Robert Lawry, Australian Bureau of Meteorology

This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky! You might also like the podcast Imagine This, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.


Where do clouds come from and why do they all have different shapes? – Ryan Potts, age 7, Canberra.


Hi Ryan, great question!

When it comes to understanding clouds, it helps first to understand water.

You know the water you drink out of a glass? That’s liquid water. There is also solid water, such as ice from the freezer or a slushy.

But water also exists as a gas. It’s called water vapour. You can’t can’t see, taste or feel this water but it’s everywhere. It’s all around you right now. Water vapour is in the air we breathe. When it’s warm and there is a lot of water vapour in the air, it can feel very sticky and sweaty.




Read more:
Curious Kids: Why do you blink when there is a sudden loud noise close by?


Now let’s go back to clouds.

For clouds to form, air needs to be cooled to a temperature at which the water vapour turns into liquid water. The best way to do this is to make the air rise, because the higher we go in the atmosphere the colder the temperature. There are many reasons air might lift, but one reason is because during the day the sun heats up the surfaces around us.

Imagine the oval near your school on a warm day. Starting in the morning the sun warms the surface of the oval and before too long the entire oval is warming up.

Warm air weighs less than cooler air. So a big bubble of warm air, filled with water vapour, slowly lifts off your school oval.

As the bubble of air (filled with water vapour) rises upwards, it starts to cool down. The higher it goes the cooler it gets.

Bubbles of warm air that have reached and passed beyond the condensation level.
Robert Lawry, Author provided

Eventually, well off the ground above your school, the bubble of air has cooled so much that the water vapour turns into liquid water. We call this point the condensation level. When the water vapour turns into tiny specks of liquid water, a cloud forms.

Clouds are simply liquid water: very, very small drops of liquid water. So small in fact, that they can be held up in the air by rising air currents.

Back on the school oval: the day keeps getting warmer, more and more bubbles of rising air race upwards, cooling as they rise. When these bubbles of air reach the condensation level, more cloud forms.

A fluffy, bumpy cloud, formed by rising warm air currents.
Robert Lawry, Author provided

Clouds formed by rising warm air currents are called “convection clouds”. Because of all the rising air coming up, these clouds can be bumpy on the top, sometimes producing very high thick clouds looking like cotton wool or cauliflower heads.



The Conversation, CC BY-ND

When air rises very slowly and gently over an area and reaches the condensation level you get a cloud that is very smooth looking, like this:

A smooth cloud.
Robert Lawry, Author provided

Sometimes air goes up past the condensation level then falls back below the condensation level, then up, then below, again and again. This creates clouds that are stripy, often with lines between the clouds.

The way the air moves creates all the different clouds we see.



The Conversation, CC BY-ND

All the grey clouds that you see contain liquid water. However, as we discussed earlier, water can also exist as a solid (ice). Clouds that are very high are extremely cold and may appear pure white. These clouds contain ice.

I used to wonder what it would feel like to touch a cloud. Would it be fluffy? Hard, soft, warm or cold?

Well, we don’t need to wonder. Because every time we see fog, we are looking at cloud.

Fog is simply air that has cooled to the point where the water vapour has turned into liquid water. That forms fog – which is really just a cloud on the ground.

So next time you see fog, go outside and touch a cloud!

Fog is really just cloud at ground level.
Robert Lawry, Author provided



Read more:
Curious Kids: Why don’t dogs live as long as humans?



Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:

* Email your question to curiouskids@theconversation.edu.au

* Tell us on Twitter by tagging @ConversationEDU with the hashtag #curiouskids, or

* Tell us on Facebook


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Please tell us your name, age, and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.The Conversation

Robert Lawry, Hydrologist, Australian Bureau of Meteorology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Like alchemists with killer precision, brown snakes make different venoms across their lifetime


Timothy N. W. Jackson, University of Melbourne

It’s spring in Australia and that means reptiles are starting to move about again. Including snakes.

The venom of the eastern brown snake (Pseudonaja textilis) is, drop for drop, one of the most potent of any venoms tested on laboratory mice.

Venoms work by targeting the bitten animal with deadly chemicals. And our recent research shows toxins in the venom of eastern brown snakes change as the snakes grow from juveniles to adults. It’s the first example of a significant age-related change in venom from an Australian snake.

It’s a beautiful example of evolutionary adaption, in which the chemistry of the snake’s venom appears to change in parallel with its diet.


Read more: Why I love surrounding myself with venomous critters


What is snake venom?

Venoms are typically a mixture of different toxins, each of which attacks the system of a potential prey animal or predator in a different way.

Sometimes toxins work together, each making the other more powerful, and sometimes they work completely independently, engaging in chemical warfare on multiple fronts.

Brown snake venom contains many toxins, but there is one toxin above all others that is responsible for the life-threatening effects of bites to humans. This toxin is a “haemotoxin”, which means it attacks the blood.

The haemotoxin starts clotting the blood at an extremely elevated rate, using up all of the coagulation factors, which clot the blood under normal circumstances. When all these are used up, the victim is at risk of bleeding to death.

In the worst case scenario this toxin, perhaps working with others, gives the system such a shock that people collapse within a short period of time following the bite. In this situation, immediate CPR can be the difference between life and death.

Why venom evolved

Venom is a tool that has evolved in snakes to help them secure a meal: it gives them a chance of overpowering animals that would otherwise be very difficult for them to subdue. Venom and its toxins are therefore “designed” (by evolution) to mess up the normal operations of a prey animal’s body.


Read more: Curious Kids: how do snakes make an sssssss sound?


The best toxins for this purpose may differ according to the specific type of prey animal (e.g. mammal or reptile), or the condition of that prey animal (e.g. whether it is active or inactive) when the snake finds it. As a result, we often find snakes that feed upon different types of animals have different toxins in their venoms.

This starts to get really interesting when you consider brown snakes, because adult brown snakes seem to have quite different diets from baby brown snakes.

Testing a venom hypothesis

Age-related shifts in venom chemistry have already been demonstrated for the venoms of a few species of pit vipers from the Americas, but not for anything even remotely related to Australian brown snakes.

This wasn’t because people hadn’t looked – several species of Australian snake had been investigated, but no evidence of a significant age-related change in venom had been found for any of them. This made sense to me, because none of those snakes dramatically change their diets throughout their lives.

Brown snakes are special – as far as we know the juveniles eat lizards almost exclusively, whereas the adults are generalists that eat a lot of mammals.

Baby snake venom is different

When we compared venom in adult and baby brown snakes, we did indeed find them to be different. Baby brown snake venom seems to entirely lack haemotoxins: instead, it’s almost exclusively composed of neurotoxins – toxins that attack nerve junctions.

What this suggests is that the haemotoxins that are so dangerous to humans (and lab mice) aren’t very effective against the lizards that baby brown snakes eat. We can make this dietary link with a degree of confidence because many other Australian snakes that feed exclusively on lizards have similar venom – no haemotoxins, only neurotoxins.


Read more: Snakebites are rarer than you think, but if you collapse CPR can save your life


We don’t yet know what this means from a clinical perspective. It may be that baby brown snake venom is less dangerous to humans than adult brown snake venom, but the opposite might also be true – brown snake antivenom might be less effective against the venom of the babies.

There has been at least one fatal bite from a very small brown snake in Australia, so they must be treated with respect at any age.

The ConversationAs always, the best policy for snakes is to leave them alone and let them go about their business, and to teach children to do the same – snakes want no more to do with us than we want with them.

Timothy N. W. Jackson, Postdoctoral Research Fellow, Australian Venom Research Unit, University of Melbourne

This article was originally published on The Conversation. Read the original article.

ALL AUSSIE ADVENTURES: With Russell Coight


Most people who know me know that I love the Australian bush and wilderness, and whenever I can I like to be able to get away from it all and head bush for a while.

Here in Australia there have been a number of television shows over the years that have explored the Australian outback and bush. A couple of years ago a different style of exploring Australia television shows hit the small screen – it was called ‘All Aussie Adventures,’ with Glenn Robbins playing the host Russell Coight. It was a send up of these types of shows and it always gave viewers a bit of a laugh with its light comedy.

Anyhow, I found some of the show on the Internet and thought I’d post some here for those interested in Australia from a somewhat different angle. A word of warning though – don’t take too much that Russell Coight says seriously (you’ll be led astray).

Visit the television shows web site at:

http://www.bigcoight.com/

 

Below: These clips show most of the first episode of All Aussie Adventures.