Lessons from the clouds

[Bundy]

Hey all, please have a look at the following pic. I have been reading "Understanding the Sky" and to be honest I am astounded as to how little knowlege I have of the sky and its many facets. I am hoping we can start a discussion inspired by the book on the clues the clouds give us about the current conditions.

What do you think is causing this?:

[Alkemac]

Global warming!

[Ou Man]

Cyclonic movement. Beginning of a tornado?

[wiskeyfoxtrot]

Nuclear explosion ? ( Mayor of Hiroshima said " What the F@*k was that ! " )

After eating a VERY hot bunny chow in Durbs ?

Later

[falconp1]

Hi Bundy

Looks to me like feld fire smoke rising in very still air and dispersing in all directions at the inversion layer. Never seen that before. What say ye.

[Bundy]

Hi Bundy

Looks to me like feld fire smoke rising in very still air and dispersing in all directions at the inversion layer. Never seen that before. What say ye.

I think you are right, very cleary there is some kind of source on the ground causing a rising columb of super heated air to reach the cloud layer. What I dont understand is why is there no cloud forming when it gets to the dew point. ( cloudbase )

The conditions based purely on what I can see seem to be seem to be stable with very little wind. would this be classed as a warm front perhaps? IE Great flying weather!

@ Alkemac, not sure if you were joking but looks like you are spot on!

How about this one? What conditions should we expect purely by looking at the cloud?

[pietmeyer]

If I see weird and dangerous looking clouds like that on the horizon I know my mother-in-law is coming for a visit. Happens all the time.

[Bundy]

If I see weird and dangerous looking clouds like that on the horizon I know my mother-in-law is coming for a visit. Happens all the time.

[DarkHelmet]

Looks like the ground view of the "Morning Glory" clouds you posted here, viewtopic.php?f=1&t=16614

[kloot piloot]

Nice topic Bundy and glad to hear you're enjoying the book !

The clouds above are cloud streets (see direction of grass stems in foreground and directon of streets). The street is continuous (later in the day they will get broken up by thermals but still be small cumulus lined up in streets).

Flying across these streets will be smooth but with lift on the windward side of the clouds, and sink on the leeward sides. But nothing serious, as long as you know what is coming.

The major advantage of cloud streets is (when flying paralel to them), is to get into the lift band under the cloud, coming off your throttle and enjoying free lift, generated by the cloud.

The colour of the bottom of the cloud is important though. In the photo it is fine, but if it becomes darker, beware of cloudsuck ! Move out of the lift band to prevent cloudsuck.

The tops of the cloud also looks smooth, but when they become whispey and jagged, expect turbulence under them.

[kloot piloot]

PS The first photo on this thread appears to be cirrus and being at high altitude, would have little effect on a quick low level flight.

The second photo, the cloud streets, are low level and created by topographics, low level winds and mostly coastal or frontal moisture. These are the ones which in general affects us microlights. And if you can recognise them, you can use them, rather than closing your hangar door in exchange for a beer.

[Bundy]

Wow Barry... thats beautiful mate. A real "Spritual experience"

Thanks for the detailed reply Roel, can you elaborate a bit on the "Cloud Suck" part? Never heard that term before.
I really must make a plan to get up there with you one morning and pick your brain a bit!

I am really glad I got this book! Problem is when you are dof like me, you have to read it 5 times to understand it... and then another 5 times to remember it!

DH, these clouds all look almost identical but the conditions in which they appear seem to differ vastly. The Morning Glory cloud is indeed a roll cloud caused by terrain/sea breeze effect and are almost always related to a standing wave, but the one pictured above is apparently called a billow cloud. From what I can gather, Billow clouds are more related to two airmasses scraping past each other causing this "rotor effect" at the boundary layer between them? In the pic you can see how strong the low level wind is. They move laterally across the sky as opposed to the Morning Glory (stationary)

Really fascinating stuff.

[Bundy]

Just showing the difference between these two. One above moves laterally, the roll cloud below is a standing wave and remains fairly fixed in position.

Here are a few more:

18_stratus2.jpg (28.66 KiB) Viewed 1927 times

These are the layered stratus clouds we are familiar with. They are indicative of stable conditions. Some of the best "Hands off" flying I have done has been in conditions like this, providing the cloud base is not too low! (Dont ask )

cirrus_clouds.jpg (30.07 KiB) Viewed 1927 times

"Random, isolated cirrus clouds do not have any particular significance. However, a large number of cirrus clouds can be a sign of an approaching frontal system or upper air disturbance. This signals a change in weather in the near future, which usually becomes stormier." (Wikipedia)

[kloot piloot]

Cloud suck is a common term used by hang- and paraglider pilots.
Developing cumulus clouds will always have a thermal (lift) underneath them. As you get closer to the base of the cloud (1000ft under the base), the lift becomes stronger to an extent where your forward speed becomes less then your upward speed. This results in not being able to run away from the cloud, but getting sucked into it with obvious disorientation and even more lift deeper into the cloud.
An unusually high climb rate under a cumulus will be your first indication of lift / thermal. In a microlight we have the advantage of the engine, and if it does come to a point where the lift really becomes abnormal, head to the nearest edge of the cloud to escape it.

The vertical forces just below, and inside a cumulus are enormous. Leave them alone. A lady pilot in the 2007 Paragliding World Champs in Australia was climbing happily under a cloud without recognizing the difference between a good thermal and cloud suck. According to her flight logger she experienced climb rates in the order of 4000ft/min inside the cloud, topped out at 32000 ft ASL. When she came around, outside the cloud, 30 minutes later, she was 15 km of track and all frozen. She survived, but a fellow pilot did not.

[Bundy]

Thanks Kloot!