This is a very early pleine air from Kroyer, I think he was 14 or 15.
The below figure studies are from his time in Paris with under Bonnat.
"When you paint the feet, look at the head" was a favorite quote by Bonnat, and the same principle can apply to landscapes too!
Here are some more pics of Kroyer paintings from the Hirschprung and Ribe collection. http://timpaints.blogspot.se/2010/02/here-are-some-high-rez-phots-from-my.html?showComment=1337863712222#c2141879013780671184