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The Cause of the Cloud: Difference between revisions
→Why was the cloud not seen before sunset?
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===Why was the cloud not seen before sunset?=== | ===Why was the cloud not seen before sunset?=== | ||
Questions have also been raised as to why was the cloud not seen prior to appearing over Flagstaff. | Questions have also been raised as to why was the cloud not seen prior to appearing over Flagstaff. | ||
To explain this, one has to understand a natural phenomenon - the noctilucent cloud. Noctilucent clouds (or night clouds) are tenuous cloud-like phenomena in the upper atmosphere. '''They are only visible in a deep twilight.''' They are made of ice crystals. Noctilucent roughly means night shining in Latin. They are most commonly observed in the summer months at latitudes between 50° and 70° north and south of the equator. These clouds can be observed only during local summer months and when the Sun is below the horizon for the observer, but while the clouds are still in sunlight. | |||
They are the highest clouds in Earth's atmosphere, located in the mesosphere at altitudes of around 76 to 85 kilometres (47 to 53 mi). They are too faint to be seen during daylight and are visible only when illuminated by sunlight from below the horizon while the lower layers of the atmosphere are in the Earth's shadow. Noctilucent clouds are not fully understood and are a recently discovered meteorological phenomenon | |||
Given that the cloud was similar to a [http://en.wikipedia.org/wiki/Noctilucent_cloud noctilucent cloud], it would not be visible until the sky began to darken at sunset. Dr. MacDonald made no mention of the noctilucent cloud phenomena in his report. | |||
In March 2012, NASA launched five rockets off the east coast of the USA to create some of these clouds. These clouds formed rings that look like the May 1963 Life magazine photo. <ref>http://www.gizmag.com/nasa-tracer-rockets-form-ringed-clouds-at-the-edge-of-space/21972/pictures#12</ref> | In March 2012, NASA launched five rockets off the east coast of the USA to create some of these clouds. These clouds formed rings that look like the May 1963 Life magazine photo. <ref>http://www.gizmag.com/nasa-tracer-rockets-form-ringed-clouds-at-the-edge-of-space/21972/pictures#12</ref> | ||