Why does snow fall in such cool shapes?

We went to the snow last week! It took some effort and planning, taking two little dudes on a plane to the other end of the country (for those of you reading this from overseas, this flight only took an hour and a half, so don't be too impressed) and then getting them up and down mountains each day, but it was worth it. 

The two-year-old is now obsessed with mountains and snowboarding and keeps saying he wants to go back to "Keenstown". The 8-month-old was impressed for the first half hour of each trip up the mountain, then his mood generally deteriorated. Fair enough when nobody will put you down to crawl on that slippery white stuff and you're wearing a stuffy ski suit that makes you look like Maggie Simpson. How degrading!

In the flurry of planning and packing and traveling and recovering, this blog has been neglected. But here I am again, in sunnyrainy Auckland, where the winter never really happens, but where our lives do.

I can't say I saw it snow while we were in Queenstown. In fact, the weather was pretty warm the whole time we were there and the snow conditions were definitely Spring-like, with a good deal of slush at the end of each day. Despite not seeing a single snowflake land, I did get thinking about snowflake related questions, like today's Why.

Why do snowflakes make such awesome shapes?

Obviously, like other forms of precipitation, snow comes from the clouds. There is a whole lot of vapour up there milling around and eventually it needs to come down. The temperature needs to be below freezing for the vapour to form ice crystals, which will make up our beloved snowflakes.

Crystallization is one of those amazing things that happen on Earth, which remain amazing despite being explained by science. Like other crystals, ice crystals need a starting point to grow from. Often, this happens when cold water vapour hits and clings onto a dust particle, which can even be a bit of space dust. I always knew there was something mystical about snow.

Once the nucleus of the crystal has formed, the water molecules arrange themselves into an hexagonal shape, as this is the natural pattern created when you bond hydrogen and oxygen to make water.

As it falls towards the Earth, the ice crystal meets up with more cold water vapour, which attaches itself to the six sides, making the six crystalline arms you usually associate with snowflakes. Sometimes, these crystals attach themselves to other ones that are falling through the air at the same time, making the big, fat fluffy flakes I so miss from North America.

It needs to be below zero all the way down to the ground for the crystals to fall as snow, otherwise they may turn into hail or even rain.

Why is each snowflake unique?

The ice crystals grow and change as they fall through the atmosphere depending on the temperature and levels of humidity they encounter. Slight changes in temperature and humidity will distinctively change the shape of the crystal, so for this reason, with all the shifting air in the wintery sky, each snowflake is likely to form slightly differently.

Fun fact: the largest recorded snowflake was 38cm and fell in Fort Keough, Montana, USA in 1887. However, this was apparently observed by a farmer who described the flakes as 'larger than milk pans'. Sounds a bit dubious to me.

Why do we use the terms West and East to describe parts of the world?

A simple answer to this question is to point to a map. There you have it: West is on the left, East is on the right. But this leads to another question: Why are most maps set out that way?

We humans a bit obsessed with trying to order the world. We give labels to everything in it, including the tiniest molecules, so of course it follows that we have divided the actual globe into segments. These can be called the Northern, Southern, Western and Eastern hemispheres. 

Most people are aware of the Northern and Southern Hemispheres, and since the Earth spins on its North-South axis, these don't change, so they are an easy concept to understand. 

A Pacific-centred map

However, what makes the Eastern and Western hemispheres more difficult is perspective. From New Zealand, Africa, Asia and Europe would be West, the Americas, East. 

To make things clear, people got together back in 1884 in the USA and had a conference. At this International Meridian Conference, they decided to agree that one spot on the globe would be referred to as the international zero longitude reference line, or the Prime Meridian. 

Probably because of where a lot of these people originated from, they decided on a place in the United Kingdom, called Greenwich.

A line running North-South through Greenwich thus divides the Earth into Eastern and Western hemispheres. Using this point as zero longitude and the Equator as the North-South divide, we can reference any point on the globe using numbers. Clever old humans. 

What about the Western/Eastern world in terms of politics?

Err, yeah. I'm not getting into that. But, in short, these terms are often used without reference to the lines on the map. When people talk about the Western world in terms of politics or wealth, they often mean the First World. So Australia and New Zealand are the 'West' in terms of way of life, despite being in the Eastern hemisphere.

My kid is lost

I don't blame it. You will need to explain latitude and longitude. An easy way to do this is to look at a map, or even better, a globe, and point out the lines that run through it. Everything is new to kids, so to tell them that people all agree that this one line is where we divide the world into West and East should be pretty simple. 

You could get out the compass and have a bit of an orienteering session on the lawn to get directions sorted. This concept is probably a 4 years+ Why, or maybe older? Those of you with 4-year-olds will be able to tell me this...I'm still dealing with the terrific twos. Good luck!

Next time

I don't have another Why just yet, so I'm going to call for questions again. Comment below if you have one. You have two weeks to think about it. Get whying.