::Sure, thanks for opening discussion on this. I'm very open to reverting this change if solar elevation angle is more appropriate. A quick Google scholar check finds  
 ::* 45,000 results for solar zenith angle 
 ::* 3,500 results for solar elevation angle and  
 ::* 1200 results for solar altitude angle. 
 ::Results on google books similarly favour solar zenith angle as the more common phrase. However, I am not an expert in this field and am quite happy to accept my ignorance of the most common name. Do you think the two concepts are sufficiently different to warrant two separate pages, or do you think the current situation with one page for the two terms is best?