If the evenings red
And the morning's gray
It's a sign of a bonny, bonny day

If the evenings gray
And the mornings red
The ewe and the lamb will go wet to bed

References:

Web Weather for Kids:
http://eo.ucar.edu/webweather/

Clouds:
<http://en.wikipedia.org/wiki/Clouds>
<http://eo.ucar.edu/webweather/cloud3.html>

Red Sky In Morning, Sailor Take Warning,
Red Sky At Night, Sailor's Delight..:
http://www.srrb.noaa.gov/highlights/redsky/index.html