TeaTime wrote:
"oriel36" wrote in message
ups.com...
SNIP
http://en.wikipedia.org/wiki/Image:Seasonearth.png

What is a little (unintentionally) off-putting with those correct
images is that it gives no real idea of the Earth's change in orbital
orientation and it can be easily fixed by not showing the difference
between the orbital shadow and solar radiation facing in the same
direction,at least in the June and Dec images.

The only thing 'wrong' with the presentation of those images, in an
astronomical sense, is that they show the Earth with its polar axis vertical
rather than at 23.5 degrees to the vertical. The shadow and illuminated
portions are precisely what happens in reality.

Funny,funny,funny !.

Keeping the Earth's orientation fixed to Polaris and allowing the Sun
to drift up and down against the horizon denoting a variable axial tilt
to the Sun is remarkable in an era which requires a clear conception of
the relationship between axial and orbital motions and the consequences
for climate and meteorology.

The images from Wikipedia are fine apart from a minor adjustment
which could be made to demonstrate the global asymmetry between June
and December in terms of the Earth's orbital position and the
direction from which it receives solar radiation -

http://en.wikipedia.org/wiki/Image:Seasonearth.png

Celestial sphere geometers are inclined to construct a variable axial
tilt to the imaginary orbital plane whereas a more accurate view allows
the orbital path to generate the drift in the orbital shadow against
fixed axial orientation.

I well understand just how established the variable inclination is and
do not unduly criticise anyone for taking a fresh look at what causes
global climate and then what causes hemispherical weather patterns.It
is well worth the effort.