Nacreous Clouds - take 2
Finally another sighting of those rare nacreous clouds. More on flickr .
Comments
Is this related to the northern light effect?
No, not linked at all. Northern lights are caused by particles from the Sun, while this type of clouds is still unclear what it actually is. NASA just launched a mission to found out more about it (http://en.wikipedia.org/wiki/Aeronomy_of_Ice_in_the_Mesosphere).
Nacreous clouds or mother of pearl clouds will only be seen just after sunset or before sunrise, they form in the stratosphere at heights of between 6-18 miles when the temperature there falls below -80°C and are ‘probably’ composed of ice particles with a liquid coating of nitric acid tri-hydrate. They appear bright because they are high enough to be illuminated by the sun long after local sunset and the pastel colours arise through diffraction or interference effects in much the same way that colours appear in a film of oil on a puddle of water. Aurora borealis (northern lights) & aurora australis is the emissions of photons in the Earth's upper atmosphere & not connected to these clouds formations.
Rob Benedict (UK)
Life Line
Specify whether public transport stops have tactile paving
Determine the heights of kerbs at crossings
Specify whether crosswalks have tactile paving
Survey if places still exist
Survey hairdresser's customers
Specify whether kerbs have tactile paving
Determine the heights of kerbs
Specify what can be recycled in recycling containers
Specify type of recycling amenities
Specify path surfaces
Survey if places still exist
Specify whether there are cycleways
Specify whether roads have lane markings
Specify whether roads have sidewalks
Specify whether pedestrian crossings have islands
Specify whether pedestrian crossings have traffic signals
Specify road surfaces
Specify access to playgrounds
Specify whether places take fees to visit
Survey whether opening hours are signed
Specify whether pedestrian crossings have islands
Specify whether pedestrian crossings have traffic signals
Determine whether any glass or just glass bottles can be recycled here
Specify type of recycling amenities
Determine place names
Shortlink
This article has a short URL available: https://drck.me/nc-t-2-678