The definition of "No Significant Cloud"
Perhaps a silly question (for which I do apologise), but I would appreciate some clarity here.
Quite often in METARs, mostly on hazy days, I see "No Significant Cloud" displayed on the METAR; occasionally even when vis. is >10k I see NSC displayed on the METAR.
What is the definition of "No Significant Cloud"? Is it a case of there is cloud in the vicinity but not enough to say e.g. "Few at 2500 feet"?
There again, whilst not actually cloud, I would've thought that Haze would qualify as "significant" especially to us VFR folks. So why on hazy days is "HZ" rarely specified on the METAR, instead say vis. at 7K and "NSC"?
What gives?
Smithy