Question: Summer Atmospheric Phenomena: Lightning Behind Clouds ? “Heat Lightning” ? Answer: |
Subject: |
RE: Lightning
Behind Clouds? |
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Date: |
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From: |
"Canali,
Eric" |
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To: |
"Glenn
Walsh" <gawalsh@planetarium.cc> |
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"Lightning behind clouds": (perhaps?) In the summertime, cumulonimbus clouds late in the afternoon can grow to phenomenal heights as they deliver their mushrooming column of warm,
moist ground-air high into the frigid heights of the atmosphere. Like
titanic towering castles looming miles high over our ant-hill like
cities and countryside their upper reaches are often still seen
illuminated by the rays of the sun when the countryside below had long
since been carried into post-sunset twilight.
Once it gets completely dark even if the local clouds have not developed muchinternal storm activity, the lightning flashes in the tops of neighboring storm-clouds,
even ones just over our horizon 30-50 miles away can be seen reflected on the now
otherwise dark, local cloud-tops above us. Add this to the fact that the humid summer
air disperses and conducts light in all directions more effectively through diffusion
than dry air does and people experience what in semi-scientific folklore is referred to
as "heat lightning".
The folksy assumption is that mysterious subtle flashing in the hazy summer night sky,a sky that is sometimes even cloudless in your locality, is some kind of special
semi-invisible local lightning, has given birth to many impassioned but spurious explanations
for the hours of silent flashes in our muggy summer night sky.
- ERIC CANALISouth Hills Backyard Astronomers