Dilla Hookham, of Villa Maria College, asks :-
Why do we have sun-showers?
Gavin Fisher, an atmospheric scientist with the National Institute of Water and Atmospheric Research, Auckland, responded.
Sun showers are just one of the beautiful phenomena that can occur when rain is falling and the sun is shining.
Rain falls from clouds. Cumulus clouds are big lumpy clouds caused by convection (usually heating of the surface relative to the air). They can be very small, just the little puffs we see on a summer day, to very large, the tropical storms which create huge amounts of rain. Cumulus clouds are usually short lived, lasting anything from a few minutes to a few hours.
If cumulus clouds are small, they generally don't rain. However once they get to a certain size, they can produce light rain showers. Sometimes there might be just a few raining cumulus clouds in the sky with blue sky around them. If the sun is shining through the rain, this produces a `sun shower'.
Sun showers can be quite common in some parts of the world (such as the tropics), and in some seasons, especially summer and sometimes they are given nicknames. For example, in parts of Africa whenever children see the sun while its raining, they say its a `monkey's wedding'. I don't know how this has come about, but perhaps there are similar sayings in other places?
There are lots of other interesting things to be seen when the sun shines into clouds and rain. For example, rainbows are seen when the sun is behind you. Many high clouds are so cold they are composed of ice crystals and these produce halos around the sun.