0:00:05 > 0:00:08Hi, I'm Ricky with your Newsround update for this morning.
0:00:08 > 0:00:10Coming up...
0:00:10 > 0:00:11Who are you dressing up as?
0:00:11 > 0:00:16Some top authors tell us their World Book Day ideas.
0:00:16 > 0:00:17Hi, everyone, Tom Fletcher here.
0:00:17 > 0:00:25Hope you're having a great World Book Day.
0:00:30 > 0:00:34But first, the big freeze continues with many of you waking up
0:00:34 > 0:00:36to more snow this morning.
0:00:36 > 0:00:39Scotland has seen the worst of it.
0:00:39 > 0:00:42The most severe weather warning is still in place there.
0:00:42 > 0:00:46Travel has been disrupted for many - we're hearing that some people have
0:00:46 > 0:00:50been stuck on the roads all night.
0:00:50 > 0:00:52But lots of you are enjoying the weather.
0:00:52 > 0:00:55Teachers and students at a school in Essex had a snowball
0:00:55 > 0:00:58fight on a epic scale - take a look at this.
0:00:58 > 0:01:06DRAMATIC MUSIC
0:01:07 > 0:01:08Go!
0:01:08 > 0:01:16LAUGHTER
0:01:21 > 0:01:29DRAMATIC MUSIC
0:01:40 > 0:01:46The headteacher at that school is called Mr Snow, I kid you not!
0:01:46 > 0:01:49It's not just the snow that makes you feel cold on days like today -
0:01:49 > 0:01:51there's also something called the wind chill factor.
0:01:51 > 0:01:53Sounds interesting.
0:01:53 > 0:01:53So what is it?
0:01:53 > 0:01:56It is absolutely freezing at the moment but did you know
0:01:56 > 0:01:58that the temperature we feel is different to the actual
0:01:58 > 0:02:01temperature of the air around us?
0:02:01 > 0:02:03Now, outside the studios here at newsround it says it's
0:02:03 > 0:02:07around -1 degree but it also says it feels like -7.
0:02:07 > 0:02:15Now, that's because of something called the wind-chill factor.
0:02:15 > 0:02:17Weather experts often call wind-chill of the feels
0:02:17 > 0:02:19like temperature.
0:02:19 > 0:02:20It's worked out using the air temperature, humidity,
0:02:20 > 0:02:23that's how much water vapour is in the air, and wind speeds.
0:02:23 > 0:02:29All this information is combined into the science of how heat is lost
0:02:29 > 0:02:31from the human body.
0:02:31 > 0:02:34So, on a cold, windy day like today, why does it feel even
0:02:34 > 0:02:38colder than it really is?
0:02:38 > 0:02:44On a calm day, our bodies insulate us.
0:02:44 > 0:02:47we give off heat so we warm the air around us.
0:02:47 > 0:02:52It's a bit like having a warm force field or blanket.Bbut
0:02:52 > 0:02:56But when it's cold and windy, the wind hits the face and called
0:02:56 > 0:02:59the skin to almost the same temperature as the air.
0:02:59 > 0:03:02It essentially blows the blanket away so we feel much colder.
0:03:02 > 0:03:03So, there you have it, wind-chill.
0:03:03 > 0:03:05Pretty cool, eh?
0:03:05 > 0:03:07It's so windy!
0:03:07 > 0:03:11Help!
0:03:11 > 0:03:12Next - happy World Book Day!
0:03:12 > 0:03:14Lots of you are dressing up today.
0:03:14 > 0:03:16But which characters would famous authors like to be?
0:03:16 > 0:03:24They've been telling us.
0:03:25 > 0:03:29If I had to dress up for World Book Day, I have one hero,
0:03:29 > 0:03:30a writer and an actor, William Shakespeare.
0:03:30 > 0:03:33I think he's absolutely brilliant and I would love to wear those big
0:03:33 > 0:03:36baggy trousers and tights.
0:03:36 > 0:03:38For World Book Day, I'm dressing up as Harry Potter
0:03:38 > 0:03:39with his invisibility cloak.
0:03:39 > 0:03:41It's the easiest costume.
0:03:41 > 0:03:46It looks like this.
0:03:46 > 0:03:50I dressed up as the amazing late, great Louise Rennison's Georgia
0:03:50 > 0:03:54from Angus, Thongs And Perfect Snogging.
0:03:54 > 0:03:57So I dressed up as a huge stuffed olive and I walked
0:03:57 > 0:03:58up and down my street.
0:03:58 > 0:04:02One of my favourite characters is Ratty from Wind In The Willows
0:04:02 > 0:04:06because I love the fact he's always in his little rowing boat,
0:04:06 > 0:04:09so I'd quite like to be in a little rowing boatdressed as Ratty
0:04:09 > 0:04:17and reading a book on World Book Day.
0:04:17 > 0:04:20I think I'd probably dressed up as Matilda simply because,
0:04:20 > 0:04:23as far as I can remember, she always had an armful of books
0:04:23 > 0:04:26and I think that's the best way to go out into the world,
0:04:26 > 0:04:27so I'd probably pick her.
0:04:27 > 0:04:30I think it would probably be Batman because Batman
0:04:30 > 0:04:36was my all-time hero and probably is still my all-time hero.
0:04:36 > 0:04:39If I could dress up as anyone - is it supposed to be
0:04:39 > 0:04:40someone from a book?
0:04:40 > 0:04:41I think so, yes.
0:04:41 > 0:04:43Someone must have written a book about Elizabeth Taylor.
0:04:43 > 0:04:49I could dress up as Elizabeth Taylor, couldn't I?
0:04:49 > 0:04:53We can't --
0:04:53 > 0:04:55We can't wait to find out who you're dressing up as today.
0:04:55 > 0:04:58Head online to let us know and send us a snap!
0:04:58 > 0:05:02And we'll have two top authors live here in the studio in half an hour -