Add and update constants for doing solar radiation calculations.
Add and update constants for doing solar radiation calculations.

git-svn-id: acf0ef94bfce630b1a882387fc03ab8593ec6522@206 150532fb-1d5b-0410-a8ab-efec50f980d4

ahill818/MetPy,dopplershift/MetPy,ShawnMurd/MetPy,ahaberlie/MetPy,jrleeman/MetPy,ahaberlie/MetPy,deeplycloudy/MetPy,dopplershift/MetPy,Unidata/MetPy,Unidata/MetPy,jrleeman/MetPy