Why do storms produce thunder and lightning?

Stop throwing those blocks at your brother, toddler, here's my explanation of how thunder and lightning works. 

I know you've been waiting all week for the answer to this one, cos you're busy types, too busy to just google it yourself, right? Plus I totally read books (I did, we went to the library). Keep in mind, this is written to be explained to a toddler, so I've gone for simple, but not too simple. I find most toddlers are smarter than you think they are and it's best not to condescend them.

So, the first thing is the weather needs to be quite warm to make a thunder storm, so they mostly happen in spring or summer, but can occur all year round.

The warm, damp air on the ground rises and mixes together with the cooler air up high in the sky and creates a cloud. This lift can happen because of something physical, like a mountain in the way of the air, or because of a front, which is the place where two different air masses meet. A mass of hot air might meet up with a mass of cold air and this would cause the hot air to lift up over the cold air.

So, as the cloud gets bigger and grows even higher up into the sky, some of the drops of water inside it get really cold and turn into ice. The bits of water and the bits of ice crash into each other and make positive and negative electrical energy. When the cloud gets filled up, the electricity starts to escape in the form of lightning.

Think of how the magnets on a train set connect the engines with the cargo. If you hold them a little way away from each other, they jump forward and connect together. Well, the electricity in the cloud is the same. It tries to find somewhere to connect to, somewhere that has electricity in it too.

Sheet lightning, when the whole sky is lit up, happens when the electricity jumps from thunder cloud to thunder cloud. Forked lightning, the zig-zag kind, happens when the lightning hits something on Earth. Often this will be something metal, cos metal things can hold on to electricity.

Lightning is so hot and fast, it moves the air around it, creating a loud bang, which is thunder. We don't hear thunder at the same time as lightning because light travels a lot faster through the air than sound does. If the thunder sounds like a loud clap or bang, it must be close to you. If it's more like a rumble, it must be further away.

And there you have it, thunder and lightning.

A new generation of Nanas

This week, I picked out my favourite picture book, Peepo by Janet and Allan Ahlberg, to read to my 2 year old. I have to admit he's not as into it as I am, but sometimes I like to drag him behind me as I wander down Childhood Lane.

Kids' books have this hilarious way of representing stereotypes, or at least the classics from my generation do. How funny is the burglar in Mog the Forgetful Cat, with his little black eye mask and his striped shirt? Here's an image of him after he's been caught, eye mask hanging shamefully from his fingers while he enjoys a cup of tea with his victims. It took me years to realise burglars don't necessarily wear stripes and people who have been burgled are not usually so generous.

Anyway, Peepo got me thinking about grandmas. To my generation, a grandma looks like the one in Peepo. She's there in the background of this image, hanging out the washing. She's wearing a floral dress and an apron, with her white hair done in a tight perm. That is how I would draw a grandma if I was playing a game of Pictionary, even though mine don't look anything like that. I wonder if my children would recognise that image as a nana, since both of their grandmothers wear modern outfits, not overly different from mine if I'm honest, and have their hair dyed.

Which brings me to this week's Why...

Why does our hair lose its colour as we get older? Does blonde hair turn white and dark hair turn grey? Does stress really make it happen faster?

Tune in next week.