Saturday, 8 October 2016

Your questions: Snow and ice

Is the snow everywhere? 
Good question! and I can answer it with statistics, if you like numbers! (Even if you don't, the numbers aren't very hard to follow.) 
More than 98% of Antarctica is covered with ice. Only a very small area - less than half a percent - is bare rock. Part of that is a fascinating place called the Dry Valleys, and it's not too far (a helicopter ride) from Scott Base, so New Zealand scientists get to work there.  

Wright Valley in the Dry Valleys; photo by Brian McKerrow;
©Antarctica New Zealand Pictorial Collection [1969-1970]
How does the ice taste? 
I don't know how it tastes yet, but I do know you can drink melted sea ice, if it's not too new, because as ice gets older, its saltiness is pushed out into the surrounding seawater. The early explorers used to heave up hunks of floating ice from the sea, to use on board.  
You can find out more fascinating stuff about sea ice here

How old is the ice? 
One of the interesting things about snow in Antarctica is that it builds up in layers, year after year. Scientists can drill ice cores in the ice to find out how old it is, and what the climate used to be like (a bit like dating a tree by the rings in the trunk). The ice cores can go back hundreds of thousands of years. 

I want to know how thick different pieces of ice are and how much weight they can hold. 
Some of the ice is thick enough to hold a plane! 
Thanks for this great question because it's made me find out a lot more about runways. (I guess it's important to trust them when you are flying to Antarctica!) 
There are several different sorts. Ice runways are made early in the summer season and can be used until the sea ice (which is about 2 metres thick) starts to melt and go slushy. 
But there are also snow runways that can take smaller planes (like ski aircraft) and then there are blue ice runways. These are on areas of ice that have no snow on top, and even if snow falls, the wind and evaporation take it all away. The blue ice is strong enough to support wheeled planes carrying heavy loads.  
Travelling from New Zealand, you land on the Pegasus Ice Shelf Runway or the Williams Field Runway. You can read about them here
Here's an article about the ice runway at McMurdo Sound, and you can see some more photos of it here

Approaching the McMurdo sea ice runway through the cockpit window; Photo by David Geddes 
@ Antarctica New Zealand Pictorial Collection [1988]
If you squirted water out of a bottle, would it freeze? 
I can show you a very cool video clip about this. Imagine you are inside at Scott Base, and you go outside (just for a moment, with plenty of warm clothes on!) and toss some boiling hot water into the air. What would happen?
Here's Dr Ed Butler showing you what does happen
(Complete with scientific explanation as to why, in the comments below.) 

Why does the sun not melt the snow/ice?
Because there's such a lot of it, and it's so cold! 
If you think about the snow and ice here in New Zealand - e.g. on Mt Ruapehu - a lot of it will melt away over the summer. But the Antarctic ice sheet holds about 30 million cubic kilometres of ice. I can't even imagine how much that is - it's enough to cover the whole of  Australia in 4km of ice.  And not only is there heaps of ice, but the temperatures are incredibly cold, so it never gets warm enough to melt much, even when the sun is shining. 

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