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Weather signs

Not really a rant this time out, but a reminder.

If you grew up in a house with two adults, chances are that at an early age you developed a respect for their bedroom door. Sometimes it was okay to go through that door, and you were welcome and made a fuss of, and sometimes you went through the door to find the big people engaged in grown-up stuff, and you certainly weren’t welcome and got thrown out in a hurry.

Every launch should involve a decision as carefully considered as the one to push through that door, as some days the sky welcomes us and plays with us gently, and some days we are not so welcome and the play is rough. Just as when we were kids the sounds that came from the closed door would give us a clue as to reception we might get, so a good look at the sky will give us an idea if it’s going to be flight or fright we run into after committing body and soul to the sky’s embrace.

As summer heats up, the humidity increases and this is what makes our summer weather so unbearable, it’s not really that hot. I’m not going into a long discussion on the latent heat of evaporation since there’s a tutorial on that subject and most of you had the lecture back in Novice training. Remind yourself of how quickly those innocent looking cu’s can blossom into big ominous clouds and an otherwise fine flying day can OD.

Some things which should make the fly / don’t fly decision pop into focus:

  • High lapse rate or K-index predicted.
  • High humidity coupled with high visibility.
  • Small clouds quickly grow into large, tall ones.
  • Cloudbase is dropping while you watch.
  • Everyone in the air already is pulling big-ears or some other rapid descent
    technique.

If you see anything on this list while on launch, don’t take off. If you’re in the air, go land:

  • Lightning or thunder (duh).
  • Other pilots using desperate measures to get down (full stalls, deep spiral dives).
  • Rain close by.
  • Rapid overdevelopment to the point where all the blue holes and sunny patches on the ground are rapidly disappearing.
  • Extreme vertical development, clouds boiling into the stratosphere.

Summer flying can be a lot of fun for the novice as it’s often very easy to stay up for long flights. Just take 10 minutes before taking off to see it’s okay to go through the door and while you’re up there, keep a look out for signs that your welcome is wearing off.

Resources

How to read a skew-T

How to avoid cloudsuck (.pdf file)

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