Atmospheric optics

   Descriptions - explanations - images
     Arbeitskreis Meteore - German/English AKM site
     Glows, Bows & Haloes - Richard Fleet
     Légköroptikai jelenségek - Hungarian Observer Group
     Optics of the Atmosphere - Tomáš Tržický
     Paraselene - Eva Seidenfaden
     pphv - Peter Paul Hattinga Verschure
     SBGO - Mats Mattsson
     Weather Photography   Harald Edens
     Causes of colour - Dieter Zawischa

     Wikipedia articles on atmospheric optics are not recommended - many errors and omissions.

   Images
     Claudia & Wolfgang Hinz - Atmospheric Phenomena - Home
     All the Sky - Till Credner and Sven Kohle
     Australian Severe Weather
     Cloud Appreciation Society
     Ern Mainka Photography
     Atmospheric phenomena - Rob Kaufman
     Atmospheric phenomena and sky - Jari Luomanen
     Laurent Laveder - www.photoastronomique.net
     Sky Show - Vincent Jacques
     Steve's Atmospheric Phenomena


Atmospheric refraction

   Green Flash
     Andrew Young's definitive account
   Distorted suns, mirages
     Polar image - Pekka Parviainen's images


Water Droplets

   Brocken spectre chasing
     Touching the Light  Ken Scott
   Mie scattering
     Optics of a water drop   Philip Laven

Ice Halos

     Atmospheric ice halos   Bob Fosbury
     Halo Observations - Ismo Luukkonen
   Software
     HALOSKY  Solar altitude and appearance of halos at any time - Mark Vornhusen.


High Atmosphere

   Nacreous clouds
     Norway nacreous clouds  Arne Danielsen
   Noctilucent clouds
     Noctilucent Cloud Observer's Homepage  Tom McEwan
     Polar image - Pekka Parviainen's images
     Clear Skies - P-M Hedén's images   
     Kark Kaiser - NLC section
    
   Aurorae
     Formation & explanations
     Physics of the aurora - UCAR/COMET (Need to register)
     Aurora FAQ - Univ. Alaska, Fairbanks Geophysical Institute
     Predictions & alerts
     Spaceweather
     NOAA POES - Auroral ovals & activity
     Observing guidance and images  
     Images of the Aurora - Jan Curtis, superb image collection
     Images
     Aurora Galleries (Spaceweather)
     Clear Skies - P-M Hedén's images   
     Fredrik Broms - 'Northern Lights Photography'
     Geir Øye's images

Clouds & Weather

     Cloud Appreciation Society
     Cloud & Storm Links - Thanks Matt