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Re: Private Universe and the Seasons



At 01:24 PM 9/19/2003 +0200, Mark Sylvester, you wrote:
///
One misconception that I've come across,//
is that the hemisphere tilted away from the sun is in winter
because it's further from the sun, and likewise the summer side is in
summer because being tilted towards the sun it's closer to it.

I take it that "light flux" (above) means the watts per square metre, while
"illumination" refers to the fact that a given square metre is illuminated
for more hours per day in summer. //. It would be interesting to determine the
relative contributions of the two factors.

Mark
Mark Sylvester


Mark's question about relative contributions of solar normal
intensity, day length and solar distance set me to pondering.

I easily found a latitude and daylength extrema at Chicago,
so I tried an estimate based on this location.
Taking the noon intensity as (Summer)
700 watt * cos (LAT - LAT of Tropic) * 1/ solar distance increase

(Winter)
700 watt * cos (LAT + LAT of Tropic)

Using Chicago Lat = 42 deg N, tropic at 23.5deg N
Gives me Summer 700 * 0.95 * 0.97 for 15 hours of daylight...
Winter 700 * 0.41 * 1 for 9.5 hours of daylight.

This seems to indicate a 2.2 ratio of Summer/Winter solar
intensity and a 1.6 ratio of Summer/Winter Daylength
using a 0.97 ratio of Summer/Winter Solar distance
which leads to an estimated seasonal contribution of
58% for solar intensity increase
and
42% for daylength increase.

Brian Whatcott Altus OK Eureka!