AtlanticFlamethrower

Clear blue skies again today. Just had an Air Berlin fly overhead at 36,000 feet. That's higher than most of the high planes which are usually somewhere over 20k. As it passed over it left a pretty good contrail that extended all the way across the sky. However, 15 minutes later it's virtually all gone. At this level the air is currently about - 12C with a dew point of - 20C. For really strong contrails we're looking for cold, humid air. This is cold enough but has very low humidity, which I'm guessing could be why the contrail was long but short duration.

Skew-T charts could be useful. Could work out approximate height from mb while dew point provides a measure of humidity - if I read the chart correctly. According to this. 600mb = 14,000 feet 400mb = 25,000 feet 250mb = 36,000 feet 150mb = 46,000 feet So this chart of 12pm today when there were short contrails suggests... judging by 500mb - 400mb level (20-25,000 feet), dewpoint was between -10C and -17C (the lower side). Presumably on Sunday the dewpoint was higher, so the water vapour from the jets did not have to cool so much to condense, because the contrails on that day were persistent. I don't know this though because I don't have skew-T plot from Sunday. I'll have to check another day to see if this works.

I'll periodically return to this thread, so if you've only just read it and it's about two weeks after I've posted it, I'm still interested. I'll post here with an update as soon as I find the information elsewhere.

Hi, I've just been walking outside. Beautiful clear blue skies, and the few airplanes there are in it are like comets, shooting across the sky with short white contrails behind them. This is different to yesterday. Sunday the jets were leaving persistent contrails. Sunday was a pretty good day like today. What is the difference that explains the short contrails we have today and the ones that covered the entire sky yesterday? The difference may have something to do with temperature and humidity. What charts can I look at which show this so I can predict which days will have short and long contrails ... and by extension, by looking at contrails alone be able to know what the temperature/humidity is like at certain heights in the atmosphere. You can track the heights of the contrails using flightradar. http://www.flightradar24.com/ Any help answering this question and links appreciated.

7.3C

Only just arrived here last 5 minutes. Obviously a long way down from the cloud!

5

1.5C

The Scandinavian high is always moved further west than initially projected and the models are always keen to blow it away quickly with low pressure systems that eventually prove not to be as strong as they say they're going to be (or disappear entirely by +48). Nothing has changed. Models are not as accurate in blocking set-ups.

Remember local sea temperature (north sea, irish sea, channel) is affected by cycles. If you're sitting in a warm bath then you are going to remain, on average, that bit warmer when someone opens the bathroom door and lets all the cold air in than if the same happens when the bath is cold. Winter is my worst time for guessing. I think I predicted 5.0c this month. If it is anywhere close it will be a first for me!

5.0C

Thanks for the competition, as always. If I can have a better winter season I would stand a better chance of winning. It seems to be where I lose the most points. In this part of the world the winter months are the most difficult to predict because it can be mild or freezing.

3.7C

8.2C

It's happening right at the start of the month which is, on average, warmer than the end. If it was projected for mid-month I personally would have gone higher but warmth at the start of the month has more opportunity to be cancelled out later. I do wonder if I'm on the cold side... but if we get this high in a slightly different position and some clear skies the CET could change pretty rapidly.

Only four pages this month so maybe I'm not the only one to have forgotten this month? Always leave it to the last hour of the last day though so had to happen sometime! 10.1C Edit: this is a late entry.

Square cloud

17.6C

Dutchsince thinks they'll be an 8.0 within the next few weeks.

14.3C

Video from the same passenger jet http://www.youtube.com/watch?v=OfxCkpTB5zY&feature=channel_video_title

11.6C

Paul T, UAH satellite record (Ch05 is used, first link) actually shows cooling recently, which goes to show you cannot judge what is happening to the whole world by local anomalies. http://discover.itsc.uah.edu/amsutemps/ http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt It certainly has been a hot April - will it continue into May?

Actually I was originally going for 11.5C, but then I turned to the last page and found RJS had got there first! 11.6C might yet be closer...

http://www.youtube.com/user/dutchsinse#p/u/1/nx_uUu6ZRYw Found a whacky youtube channel that covers Earthquakes. Should interest some people. Wonder what the software is he's using.