Is human pollution causing clouds to form near the edge of space?

Noctilucent clouds, which glow after sunset, are the highest known clouds in Earth's atmosphere

Late spring/early summer in the northern hemisphere is a good time to look for noctilucent clouds. Roughly translated from Latin, noctilucent means night shine", which is a good description of these beautiful cloud formations. They can be seen glowing an electric blue colour against the darkening western sky about 30 minutes after the sun sets.

Noctilucent clouds are the highest known clouds in Earth's atmosphere, existing at an altitude of about 80km, which is virtually the edge of space. The Karman line, which marks the boundary between the atmosphere and outer space, is defined as being 100km in altitude.