Definition of Cloud

[SkyHog]

Ok - now desire to live not withstanding - what is the technical definition of a cloud?

I ask because we have in the past (not lately, mind you), had a very thick "Brown Cloud" of pollution hovering over the city. Ever since Albuquerque has started to care about pollution, its getting better, but someone asked me if we could fly in that, and I didn't know the answer.

I would assume no, because visibility would go to pot - but is it considered a cloud as far as the 500 below, 1000 above and 2000 lateral spacing requirements are concerned?

Also - what about other types of strange formations - like low lying fog. Are you required to be 1000 feet above it, and considered flying VFR over the top over a low lying fog layer?

 

[fgcason]

Seemingly such a simple question isn't it? I'll have to think about this today...

Seeproof air?

On a practical level, I think the operational visibility inside the reduced visibility area is a contributing factor to being defined as a cloud and treated as such. The entire East Coast is a cloud compared to the Front Range of Colorado but they're still flying VFR in the region. I've seen smog domes over cities before and while it's horrid compared to the surrounding area, it was still 5-8 miles visibility inside that area and there was no major transition issues with the sun making it a seeproof wall in front of you as you entered it. VMC or IMC? If you were to see a wall in front of you due to sun angle that would be an issue and should be treated as a cloud lest something pops out the side and bangs into you.

I suspect that if you can see completely through an isolated cloud or the visibility is VMC (3+ miles) inside it and you can see the horizon then it's really not a cloud from an aviating point of view.

Practical operations question: If you have 50-75 miles of visibility in all directions and there's an area 5 miles across right over your spinner that's roughly 6-7 miles visibility inside if it were larger (reduced visibility but you can see completely through it and see mountains on the other side and the ground/horizon below the suspected cloud), do you fly through or maintain cloud separation? I think cruise on...

Ground fog? Same kind of category as cloud caps on mountains or fog filled valleys. Depends on the thickness I think. 1000ft thick over an airport, no thoughts needed. 20-40ft thick ground fog in the middle of farm country, probably not much of an issue since nothing is going to be coming out of that to run you down. 500ft thick in unflyable valleys? Needs more thought for today... But technically they could probably throw the book at you for it.

 

[EdFred]

I figure if I can see through it, it's not a cloud. I've blasted through those wispy cloud-like formations. If I can't see through it, I'll apply the 152 or 111 rule.

 

[poadeleted20]

I figure if I can see through it, it's not a cloud. I've blasted through those wispy cloud-like formations. If I can't see through it, I'll apply the 152 or 111 rule.

Ditto.