Spanish Oddities
Nacreous clouds move south from the Artic to Madrid
By h.b.
Feb 20, 2008 - 3:11 PM

Nacreous clouds of polar nitric acid will be seen for the first time from Spain this week, giving rise to a dramatic colours in the skies. The clouds create very low temperatures as they form at more than 20 kilometres above the earth.

News of their movement has been given by the Chief of Research and Atmospheric Instrumentation at the National Aerospace Institute INTA, Manuel Gil. He said the clouds are formed by a mix of nitric acid and water and can take temperatures down to -78 degrees centigrade.

The time to look for the nacreous clouds is at dusk on a clear evening, but the Spanish weathermen say the current conventional clouds over most of the north of the country will mean few will see the phenomenon, which is however expected to reach as far south as Madrid.