What does "plein air" refer to in painting?

"Plein air" refers to the practice of painting outdoors, where artists directly engage with natural light and the surrounding atmosphere. This approach allows artists to observe and capture the nuances of light, shadow, and color as they appear in the environment at a specific moment in time. The term is rooted in the French phrase "en plein air," meaning "in the open air," which reflects the essence of the technique.

This method gained popularity among Impressionist painters in the late 19th century, who sought to depict the fleeting effects of light and weather in their work. This contrasts with other methods such as painting from photographs, working in a studio, or using digital tools, as those approaches do not involve the direct observation of the outdoor environment that plein air painting emphasizes.