Why the Mountains "Atract" the Clouds?

Mountains covered by dark clouds in Brainard Lake Recreation Area, Colorado.
Clear skies all around and dark clouds over the peaks by the Brainard Lake Recreation Area in Colorado. 

Hiking to Blue Lake I took this picture. The bad weather is concentrated on the high peaks. This is common in mountains. It may look like if they attract dark clouds. All due to the orographic lift effect. Moist air raises up through the slopes and forms clouds. Then comes rain or snow. This is more common in the windward side of a mountain range.