Light & Height
OK, I’m not anywhere near being Flaubert, so I do not seek the mot
juste.
I’m also declaring my independence to blog about the nebulous
and quite possibly the trite and the obvious – and to do it shamelessly.
The Sun is largely high in the sky, ignoring sunrises,
sunsets and high latitudes.
We tend to replicate this in our homes, although lights are
more often on walls than ceilings – and rarely on floors.
Trees (almost) always grow upwards, towards the big light in
the sky. They are phototropic.
Height is an advantage – the taller trees have unfettered
access to sunlight.
For humans, the taller you are, the farther you see. In the
savannah that humans are widely supposed to have grown up in, height would
allow one to spot both predators and prey in advance. Of course, one could have
climbed up a tree to scan the far horizon – if there happened to be a tree nearby.
In the sea also, a tall captain would help – but sailors
solved the problem of spotting storms early by putting a lookout on the mast.
Anyway, the area that can be scanned is directly
proportional to the height – of the human or the vantage point.
But the point is that the upward direction is associated
with more light and increased viewing area. Conversely, if you are shorter or
if you are stuck in a pit or a deep valley, you will have a smaller amount of light
and a decreased viewing area. So a downward direction is associated with less
light.
An extreme example is the concept of building a very high
tower at the South Pole that is permanently in sunshine - or a solar collector in low Earth orbit. Either could be used to
generate solar energy.
The tower would be 527 kms high on Earth, assuming a
perfectly spherical Earth (for R=6400 and q=22.5°).
Of course, you would have to add about 18 kms to the height of the tower, since
the polar radius (6353 kms) is less than the mean radius (6371 kms).
Note: The geometry is obtainable from the gif link mentioned below.
