Nacreous clouds

Clouds that have a vivid iridescent appearance. They are formed of small droplets which scatter light in such a way that creates the distinctive luminescent appearance. Nacreous clouds form below -78 °C temperatures at altitudes 68,500 - 100,000 ft above the Earth's surface (in the lower stratosphere) over polar regions.They are also known as Polar Stratospheric Clouds (PSC) or 'mother-of-pearl clouds'. 

Morning glory

Rare, elongated cloud bands (visually similar to a roll cloud, or arcus cloud) that usually appear in the morning hours, when the atmosphere is relatively stable. Morning glory clouds result from perturbations related to gravitational waves in a stable boundary layer. They are similar to surfave water ripples with several parallel morning glories often seen spreading in the same direction. 


A seasonal shift in wind direction that brings alternate very wet and very dry seasons to India and much of South-East Asia. It is a thermally-driven wind arising from differential heating between a land mass and the adjacent ocean that reverses its direction seasonally.


The climate of a small area, such as a garden, a location near a body of water, a valley or a city can be distinct from that in the general, surrounding region. The spatial scale microclimates can manifest over can vary from a few square metres up to several square kilometres.