MOLINE, Ill. — Have you ever experienced rain on a sunny day with no clouds? No, the world isn't coming to end, nor is the simulation glitching. What you experienced is called a “sun shower” depending on what part of the world you are in. Depending on the time of day, you have might have experienced a serein shower instead.
A sun shower occurs when rain falls while the sun is shining, with few to no clouds seeming to be present. The name sun shower makes it sound like there is rain with no clouds. but that's impossible because rainclouds are made up of water and ice particles.
There are two scientific explanations for how we can experience sun showers:
1) Presence of strong prevailing winds
The raindrops that fell while you saw the sunny skies were formed in a cloud. Sometimes, rain showers can occur at the same time as strong prevailing winds. This is most common in cumulus clouds that go higher up into the atmosphere. In this situation, raindrops can take several minutes to reach the ground.
A strong wind blowing in the same region can carry the rain several miles away from the cloud that it came out of. The rain can then fall in a different area where there are no clouds, catching people there off-guard.
2) Rapidly dissipating clouds
As explained in the previous section, it can take rain drops several minutes to reach the ground after they fall from a cloud. The time it takes for raindrops to fall from a cloud is important for this scenario.
This time, a cloud also needs to be close to dissipating. This type of cloud has very little moisture left to form water droplets, or rising temperatures in the cloud make reaching the dew point temperature impossible. When a raindrop falls from this cloud, almost no moisture is left and, with its inability to reach dew point temperatures, condensation can no longer occur to form raindrops.
As a result, the cloud starts to dissipate rapidly after the last raindrop falls from it. By the time the raindrop hits your face and you look up, the cloud is long gone.
What's a Serein Shower?
A Serein shower is like a sun shower, but the difference it depends on the time of day. A Serein shower occurs for the same reasons as sun showers, but during or after sunset.