Unusual Weather Phenomena

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Interesting weather phenomena occur every day in many areas of the world. Here is a brief look at some of them that you may have seen.

I’ve always been a big fan of weather and meteorological phenomena. Even just a thunderstorm can catch my attention with the way it forms. These five unusual events in weather are some that many of you may have seen before, but they are always fascinating to learn about.


A halo is a phenomenon that occurs because of the particular shape and orientation of ice crystals in cirrus clouds. Depending on their shape and location, these ice crystals can produce an optical halo around a bright light source. Therefore, halos can be seen around the sun or moon.

The colours of a halo can differ, like a rainbow, depending on how it is dispersed after reflection and refraction. Similar phenomena include the rainbow itself, icebows, and light pillars.

Light Pillar

Another visual phenomenon in weather, the light pillar is very similar to the halo. However, while the halo is circular, the light pillar stands straight in the sky. For a light pillar to appear, there must be a reflection of light from ice crystals with close horizontal parallel planar surfaces.

Light pillars can also reflect from bright surfaces such as the sun or moon, in which cases they are named after the body of light they are reflecting from (i.e. sun pillar or moon pillar).


Not found in most dictionaries, the sunshower is a common weather phenomena in which rain falls while the sun is shining outside. This phenomenon is referred to as a “sunshower” in many countries including Canada and the United States. Cumuluform clouds allow the sun to be seen while they are producing rain, and thus, a sunshower is born.

It is said that if a sunshower occurs during the day, it means that it will rain again some other time throughout the day/night.


The aforementioned visual phenomenon of the halo is relevant in explaining the sundog. A sundog (or parhelion) is another optical element that is seen because of the refraction or reflection of ice crystals in cirrus clouds. This sounds similar to a halo, and it is, but a sundog occurs on the halo itself. Rather than just being a reflection or refraction of light, the sundog is a bright, circular presence on the halo. On a halo, a sundog can appear on one side of the sun or moon, or on both sides.

Misaligned ice crystals produce more powerful and colourful sundogs, while light passing through the crystals at angles that don’t deviate past 50 degrees give the sundog its tail.


Having been a person who has experienced this recently, thundersnow is just a thunderstorm during winter. Obviously, this means that it would be snowing during a thunderstorm, instead of having rain as the precipitation. There are four different kinds of thundersnow which can occur:

1) Thunder and lightning in a snowstorm (Pretty simple explanation, eh?)

2) A thunderstorm on the leading edge of a warm front or cold front that can appear in a wintery environment or move into a path of cool air. Thus, the rain would turn to snow.

3) A synoptic snowstorm in the comma head of an extratropical cyclone that maintains a strong vertical mixing. These conditions would be favourable for thunder or lightning to make an appearance.

4) Lake, sea, or ocean effect snow that has cold air, which passes over somewhat warm water, and then continues to move over land. This is common in the Great Lakes region in Canada and the United States. Since I’m in this area, I see this a lot. Usually, it’s in the form of snow squalls, which are blankets of snow that are unpredictable. One minute it could be sunny, and the next, you’re covered in a foot and a half of snow. It’s usually on and off throughout the day when it is forecast for that day.

Here’s how thundersnow can form:

There are more weather phenomena to be explored, but those will have to wait for another day. These ones are fascinating, especially when you see them first-hand. Enjoy!

Source for all images: Wikipedia


Cristina Mergas
Posted on Mar 3, 2010
Posted on Mar 3, 2010