Sunrise over London

By Edward Gryspeerdt

The article for this week has been delayed, as the paper it is about is waiting to be typeset. Instead, here is a timelapse video of sunrise over Imperial from last week.

Contrails typically form at higher altitudes (because that is where the aircraft are flying). These contrails are at about 10 km altitude, which means that as the sun rises, they get lit first by the sun. This is why they are so bright in this video.

The lower lying clouds are a very dark grey. Does this break one of our three rules for clouds?

Not quite - these clouds are dark because the only light is coming from the sun, and they are reflecting it back towards the sun (and away from the camera). If you were looking at the clouds from the other side, they would appear white!