How accurate are long term weather forecasts?

On the Autumn Equinox, here in Britain our minds start to turn to the prospect of snow. And, of course, the Daily Express runs their annual dramatic headline of the worst winter in years, but how good are weather forecasts? The Met Office has recently said that four day forecasts are now just as accurate as the one day forecasts in the mid 1980s. But as far as long term, 30 day forecasts are concerned we may well be waiting a while. Because the atmosphere is so chaotic, tiny observational errors occur all the time. Tiny they may well be, but they're the kind of errors which make a huge distance!

#eclipse2015 - As it happened

Unfortunately the British weather let us down - it was very cloudy! Although it did get darker as 83% of the sun was blocked by the moon everywhere in the UK. Because we didn't actually see anything I thought I would round up some of the stunning images which have been circling on twitter and the internet today.

Here's a round up of what happened from the Telegraph

The Great British Weather - Thunderstorms!

It's fair to say Britain isn't best known for its excellent weather and roaring sunshine. Over the past week or so, we haven't been far off the roaring sunshine - it's just it's quickly followed with rather dramatic thunderstorms! Thunder causes lightning - this is essentially a stream of electrons flowing either between clouds or from a cloud to the ground. The air surrounding this electron stream is heated to around 50,000 degrees Farhenheit. It's a staggering three times hotter than the surface of the sun. When the lightning is within our sight, we see it first as the speed of sound in air is considerably slower that that of the electron flow. The light from the flash reaches us in a fraction of a second, whereas the sound lags along like a snail following an interplanetary rocket.

Follow the rest of my #SummerofScience and me on Twitter @Sci_Sparks. Don’t forget to download my charity eBook, Science Bites: A Short Tour of the Universe HERE. 

Does the Sun's cycle influence our weather?

The Sun's magnetic field constantly changes - the Sun's polarity reverses every 11 years. This activity changes the number of sunspots on the Sun's surface - this then peaks at the 'solar maximum'. The Sun's activity cools areas on the Sun meaning they appear darker. The solar cycle can also cause small changes in the Sun's heat and light output. Some studies have shown some link between few sunspots and cold winters in Europe. Although it's unclear the Sun's cycle could influence our weather.

The Perseids Meteor Shower will leave "celestial pollution"

In the last couple of days you may have wrapped up warm and gone outside to view the Perseids Meteor shower if you were lucky enough to have clear skies. During these last couple of nights, in some locations up to 60 were visible in an hour. These are caused by comet dust burning up and vaporizing in the atmosphere. These 'shooting stars' can be travelling up to speeds of 36 miles per second as it begins to burn up in the atmosphere. 

This Perseid Meteor shower are byproducts from the comet: Comet 109/Swift-Tuttle which passes earth every so often. 

Scientists at the 'Gemini Observatories' believe that they will leave behind a trail of what is known as 'celestial pollution' which is a mixture of gases. One of these being Sodium which collects in a layer in our atmosphere about 60 miles up from ground level. 

Scientists have found this to be true because they can use Sodium lasers to 'excite' the sodium so they can actually create artificial meteor showers anywhere in the world that they have these lasers and whenever the scientists want. 

Why has the UK had such hot weather this July?

June saw the weather across the UK as decidedly mixed with some good weather, but interspersed with this, we saw many spells of wet and windy weather. This was due to the jet stream being across the Atlantic, slightly further south than what is normal for this time of year. 

A major change took place just after the start of July as the jet stream took a dramatic shift northwards. This meant that the newly placed jet stream deflected the bad weather towards Ireland and Scandinavia. Then high pressure was dominant across the UK, in meteorological terms this is known as a blocked pattern. At this time of year, high pressure generally signals good weather and this coupled with the strength of sun can bring very high temperatures 

One thing unusual for the UK is that most of the UK has benefited from this good weather, and these high temperatures haven't been confined to one area. Also we have had very few thunderstorms in the last few weeks. Most people think that these always accompany the hot weather, in this case it is because the hot weather isn't from France or Spain. 

However this hot weather isn't good for everyone, the Met Office and Public Health England have been collaborating to provide advice through the Heat Health Watch. 

Compared to last year, this hot weather is in complete contrast when we experienced a succession of weather systems that we got from the Atlantic. There was no recorded change to the position of the jet stream it was a constant feature throughout the summer of 2012.

What causes heat haze?

The appearance of any object depends on the optical properties if the air between you and the object or person. These are determined by the density and temperature of the air, so any source of heat, maybe from a barbecue or the sun can cause uneven changes to the density of the air. These changes produce optical distortions which we know to be heat haze.