1. Trailblazer

    Altitude and contrail persistence

    Looking out of my window around sunset this evening I noticed a succession of planes lining up from the west, all with short contrails except one which was leaving a lengthy persistent trail. I thought it would make quite a good illustration of how "adjacent" flights can be at very different...
  2. Mick West

    Converting mb (pressure) to altitude, and sites where this is useful

    When studying contrails, you quite often come across diagrams and charts where instead of the altitude in feet or meters, we are given a pressure value in mb (millibars, sometimes also labeled hPa, which is exactly the same unit) For example, on the excellent site, we have...
  3. Marine0811

    Do contrails form around low level clouds? [Generally not]

    Why do lower chemtrails last longer than higher chemtrails? Why do commercial planes fly at least up to 35,000 ft before levelling off, but chemtrail planes level off at lower clouds around 6,500 ft.?
  4. Mick West

    Two planes at the "Same" Altitude, only one leaves a trail

    Via Twitter: The first thing to notice here is that the planes are not actually the same type: But even if they were, the visual difference in size between a plane at 36,000 feet, and another at 38,000 feet is just 5%. In this image, the visually smaller plane on the left is 57 pixels long...