When delivering a weather forecast, the broadcaster pays particular attention to whether the wet weather is rain or showers, but what is the difference? Many people think that showers are shorter or heavier than rain, but this is not always the case. The real difference is simple - it just depends on the type of cloud it comes from.

Rain comes from 'stratiform' clouds, layered clouds that often cover the whole sky. They are generally a uniform blanket of cloud, so rain is often a steady blanket too. It can stay around for many hours and then it is called 'persistent'. Rain does have exceptions though and can be more fragmented to give 'outbreaks of rain'.

On the other hand, showers come from 'convective' clouds. These are the fluffy 'cotton wool' cumulus clouds, or the larger, more threatening cumulonimbus clouds. Cumulonimbus clouds often give thunder and lightning, as well as a shower of rain, or hail. Both these clouds are generally quite well spaced out, which is why showers are often described as 'isolated' or 'scattered'. Being so isolated, it is virtually impossible to determine exactly where a shower will form. This is a problem for forecasters because between the showers there is often beautiful blue sky.

Cumulus clouds are formed by the air mixing, which is often caused by the earth's surface heating the air near to it. This causes the air near the ground to rise, and hence mixes it. During the summer, the sun heats the ground daily. As it heats up it can trigger off enough mixing to form convective clouds. This is why showers often form during the day in summer, and die away over night.

During the winter it is the sea that heats the air, as sea keeps its summer heat better than the ground. This is why in winter most showers form over the sea. If there is a wind, these showers can be pushed onto the coast. This is why tornadoes in this country, which come from cumulonimbus clouds, have been spotted in coastal resorts.

One thing that is consistent for both rain and showers is the shape of the raindrop. The familiar teardrop is not actually correct. Raindrops are actually shaped more like a hamburger bun, no matter what cloud it came out of.

Other features in the Weather Basics series:

- Clouds
- Day and Night
- Fog and Mist
- Fronts
- Frost
- High Pressure
- Humidity
- Jet Streams
- Lightning
- Low Pressure
- Mirages
- Northern Lights
- Rain or Showers?
- Thunder
- Watercycle