Most conventional aviation activity takes place in the troposphere, and it is the only layer accessible by propeller-driven aircraft. However, ionization in the mesosphere largely ceases during the night, so auroras are normally seen only in the thermosphere and lower exosphere. Our tour leader went the extra mile (literally) to make sure we got to some great locations even when the weather was bad.

Blue light is scattered more than other wavelengths by the gases in the atmosphere, surrounding Earth in a visibly blue layer at the stratosphere, above the clouds of the troposphere, when seen from space on board the ISS at an altitude of 335 km (208 mi) (the Moon is visible as a crescent in the far background).

During the day the planetary boundary layer usually is well-mixed, whereas at night it becomes stably stratified with weak or intermittent mixing.

Stratospheric ozone depletion is caused by air pollution, chiefly from chlorofluorocarbons and other ozone-depleting substances. It contains the ozone layer, which is the part of Earth's atmosphere that contains relatively high concentrations of that gas.Often taken from a low altitude, they reveal the imprint of human civilization on the face of the globe. Lightning-induced discharges known as transient luminous events (TLEs) occasionally form in the mesosphere above tropospheric thunderclouds. This includes the tape, airbags, bubblewrap and biofill (commonly known to as loosefill, international only), and of course the boxes and catalogues themselves.