All three pictures are full of plein-air effect, the one at Verona especially.
This was the sentimental echo of his former genuine enthusiasm for plein-air effects.
About 1881 he seems to have exhausted his direct interest in the plein-air movement.
Of course, plein-air painting was at first the chief object of their endeavours.
But in the orchestra of Strauss, the color-gamut of the plein-air painters got a musical equivalent.
1894, from French phrase en plein air, literally "in the open air." The style developed among French impressionists c.1870.