Posts Tagged ‘Snow’

Why does it snow?

December 22, 2010

The Barometer guys have just published a new episode on snow. It’s another good one. I’m starting to really miss being involved with the show!

In this episode they talk for a bit about how snow forms and it reminded me of this really nice video showing the melting layer in a precipitating cloud (click to play):

In the higher levels of the cloud (where it’s really cold) the precipitation starts out as ice and snow, which falls much slower than rain. But if you look closely at about 2 km you can see the point where the ice and snow melts and becomes rain – this is known as the melting layer. The rains falls much quicker than the snow above.

It snows at the ground when the lower levels of the atmosphere are particularly cold and so the snow doesn’t melt. This is what’s been happening recently.

Snow again.

November 26, 2010

I wrote a post last winter about how the snow doesn’t mean that climate change is over.

Well, it’s snowing again.

And the warming on a global scale still hasn’t stopped:

October 2010 temperature anomalies relative to the period 1951-1980 from the NASA GISS webpage.

Britain’s snow and climate change

January 8, 2010

NOTE: This post is from January 2010. I put a temperature anomaly plot from October 2010 here and I’ll do one for November 2010 as soon as the data is available.

I’m sure most of the Brits out there have seen this amazing NASA image of Britain covered in snow.  I love satellite images and use them a lot in my research – they really help me get a grasp of the big picture.

But what does this cold weather tell us about climate change?  Well, if we examine the whole northern hemisphere and look at how the temperatures for December compared to those from the last 30 years, then we get an interesting picture:

So, northern Europe and North America were colder than usual.  But southern Europe, Greenland, the Arctic and north Africa were all warmer than usual.  The situation for January will probably be quite similar.  So, looking at the bigger picture, the recent cold conditions in the UK don’t really tell us much about climate change – we need to look on big scales in both time and area.

Proposed industry standards for the terms “TREACHERY” and “CHAOS”

January 6, 2010

As much as I love reporters using the same terms over and over again, I feel that without any clear definition some of the power of these words may be lost upon the audience.  Therefore, I propose official industrial standards for these two terms.

Treachery

Clearly, in cases where this term is used, the conditions must not be merely and/or obviously dangerous.  The situation should initially appear tranquil – perhaps a sunny day with happy rabbits frolicking on the hard shoulder.  However, over time, the road-based conspiracy to undermine and betray the driver will become clear.  A quiet malevolent laughter will be audible underfoot.

Possible alternatives: dangerous, unsafe, difficult.

Chaos

A long line of stationary cars is clearly not chaotic; this situation is, in fact, relatively ordered.  If the term chaos is used, the following should be expected:

  • At least one overturned, burning car;
  • Screaming women pulling their hair out;
  • Helicopters crashing on the horizon;
  • Complete confusion (as opposed to the clear realisation that you should have stayed at home)

[Apologies to anyone that got trapped or had an accident in the snow.]

Snow in Manchester

January 5, 2010

I’ve not gone to work today.  There’s quite a bit of snow out there.  But why?

Well, the main reason why it’s cold here is because it is winter.  This sounds obvious but it’s worth remembering why it gets cold in winter.  Earth rotates with a tilt so, throughout the year, different parts of the planet get more sunlight.  At the moment, the UK is getting less sunlight so it’s colder.

However, the reason why it is just so cold and snowy right now is a bit more complicated.  If you look at the pressure chart below then you can see that the isobars are almost parallel  from the Arctic all the way to the north of the UK.  This means that very cold air is flowing right to our doorstep.  Brrr!  Watch out further south as the front (the region where the cold air meets slightly warmer air, which produces the precipitation) moves southwards and takes the snow with it.