Every cloud has a metaphorical silver lining , but it seems global warming has a literal one : increasing the relative frequency of high - altitude clouds that fall with recherche beauty on summer night . In a succeeding humankind lacking the optical splendor ofcoral reefsor ourmost majestic cities , Pollyannas may take comfort in this compensating looker . From a scientific period of purview , however , these clouds aid confirm the validity of atmospheric models .
Most clouds lie less than 18 kilometer ( 11 miles ) above the Earth ’s aerofoil . Yet even 80 kilometers ( 50 miles ) up , there is sometimes enough piddle vapor to immobilise around specks of shooting star debris . When this happens , the cloud produced are too thin to be seen from the ground during daylight . curtly after sundown or before sunup , however , the Sun fall them up , creating the phenomenon of noctilucent ( night - scramble ) clouds .
The higher reaches of the atmosphere are unremarkably too ironical to allow this to occur . declamatory volcanic eruptions create an exception , advertise so much piddle vapor to such great heights that the clouds can appear . The first scientific record of the phenomenon come from 1885 , after Krakatoa ’s explosion .
In recent years , these cloud have become more common , even without recent major eruptions . measure out this has been unmanageable until recently , but satellites are handle this problem . Speculation that human - cause climate changecould be the cause datesto 1989 , but it is only now that the evidence has been brought together to confirm this .
Professor Franz - Josef Lübkenof the Leibniz Institute of Atmospheric Physics has study the donation of methane , the second - most of import gasoline in human share to climate alteration , which reacts to produce water vapor at eminent altitudes . InGeophysical Research Letters , Lübken cover there has been a 40 pct step-up in urine vapour 80 kilometre in high spirits at mid - northern parallel since 1871 , more than double up the volume of trash crystals . Since there is a threshold measure of Methedrine to make the clouds visible , there has been a much more dramatic increment in their frequency .
" We speculate that the clouds have always been there , but the chance to see one was very , very poor , in diachronic time , " Lübken said in astatement .
An important question Lübken has yet to reply is whether these clouds , or other phenomenon at exchangeable altitudes , are having an issue on the charge per unit of planetary warming . Clouds at lower altitudes contemplate incoming sunlight and cool the planet , while higher cloudsprevent warmth from escapingthe Earth and increase thawing . clime modelers have put a lot of travail into calculate the nett effect of both of these increasing as a result of human body process , but clouds as high as these have n’t yet been taken into accounting .
