Kaj The Cloud Guy's cool stuff

Tiny ice crystals suspended in the atmosphere refract the sunlight in a halo. These are most common when the sun is low in the sky. In this particular example, one of the more frequent halos is showcased - the sundog.

Sun pillars, like sundogs, are most typical in the mornings and evenings when the sun is low in the sky. The sunlight in this case is reflecting off suspended (or gently falling) ice crystals in the vertical, creating the pillar.

The topic of rainbows can get pretty deep, but we'll keep it simple here. The general bow shape we see is called a primary rainbow. Sunshine and rain is required for a rainbow, though the rain may not be actively falling on your head when you see one. They form by the sunlight entering a raindrop and reflecting back out

On a clear, calm night, ground fog can be rather common. While this example shows a thin layer, the creation of fog is still the same. At night, the air cools with a lack of sunlight and lack of clouds. As the night goes on, the cooler air settles low (because of density) and matches the dew point. Condensation occurs at that time, forming fog.

This example of valley fog was taken on a family trip in the early morning hours while driving through the bluffs of Wisconsin. Once again, the coolest air settles low, resulting in condensation and fog formation. Valley fog can be extremely thick and you can come up on it pretty quickly while driving!

Just like blowing on an ice cube, advection fog is most common in the winter months. In the picture above, a deep snowpack existed and an airmass with a dew point over 32 degrees moved in (advected) over the snow. As the air makes contact with the snow, it not only starts the melting process but condenses  rapidly, creating dense fog. This dense fog can persist with wind as well.

Mammatus clouds are a giveaway of inclement (and likely severe) weather nearby. They are like bubble wrap and form when cooled air from a storm's anvil top sinks slowly and condenses into the surrounding air. Because the cold air is denser and therefore sinking, the bubble shape is formed.

The atmosphere naturally scatters our sunlight into various wavelengths hence our beautiful sunrises/sunsets and blue skies around lunchtime. When smoke and haze enter the atmosphere, the sunlight is scattered even more as there are more particulates in our atmosphere, leaving us with deep red and orange color. 

A wall cloud is a localized lowering from the rain-free base of a thunderstorm. This is a sign of severe weather in the area. Not all wall clouds rotate, but those that do provide a heightened risk of tornado development.

Image credit: Chris G, taken in Hiawatha, IA

This is a low cloud at the leading edge of a thunderstorm's rain-cooled outflow. The shelf cloud itself is actually a type of Arcus cloud and is usually attached to the thunderstorm itself. This is almost always a sign of strong wind. The underside of these clouds are quite turbulent and rough looking! 

Image credit: Uncle PK, taken in St. Ignace, MI, July 2023

The exact definition of a water spout is debatable, but, it's generally a tornado over water. It's a small rotating column of air over water beneath a towering cumulus or cumulonimbus cloud. And, yes, if you are wondering, water spouts can damage things! They are most common over subtropical and tropical waters.

This isn't a cloud, obviously, but it was made in one! Hailstones begin their life cycle as small pieces of ice that are present in a thunderstorm. As the updraft of the storm suspends them, they take trips inside the storm, thereby growing rings as they collide and coalesce with other smaller stones and supercooled water droplets. Eventually, these stones are too heavy to be supported by the updraft and bam - down we go, as a hailstone! This stone pictured here clearly made multiple trips!

Image credit: Judy D 

When clouds are present in the atmosphere, they contain very tiny water droplets (or ice crystals if cold enough). They may precipitate and if that precipitation evaporates (or sublimates) before it hits the ground, that's called "virga".

This is actually quite common and occurs most often when the air near the surface level is dry. The clouds generally have a curtain look when this occurs.

 Cloud shadows are generally based on their shape, the angle of the sun and of course, how high up they are (called altitude). As the sun hits the top of the cloud, which usually stays bright white due to scattering of sunlight, the bottom of the clouds may go gray or purpleish almost.  

While these dark bottoms may make us think "rain, rain, rain", they are oftentimes just simple shadows.

 Altocumulus Castellanus clouds (or Accas) are an indication of mid-level instability and are often taller than they are wide, sometimes rather narrow. The "castellanus" part comes from their visual representation of castle turrets.

Oftentimes, these clouds may be present around warm fronts, or at the very least, give away some mid-level warmth and/or instability moving in. These clouds, if they grow enough in the vertical, can produce some showers.

 Image Credit: Jessie F. via Scott W. at Kernels Stadium, Cedar Rapids, IA

 This rope-like condensation funnel exhibited characteristics more of a landspout tornado versus the classic tornadoes you might see out of bonafide supercells. Those types of tornadoes form up in the storm itself, while landspout tornadoes often form on well-defined boundaries and from the surface upward. Regardless, we have a rotating column of air here (tornado), which made for some photo ops!

Image Credit: Chris G, taken in Hiawatha, IA.

While this is a classic Cumulonimbus cloud, look at that feature just to the left of the American flag. That almost foggy/soft feature is a "pileus" cloud. Typically, these cap looking clouds can occur at the top of cumulonimbus, but this one formed lower, likely in front of the updraft that's building closest to us. These indicate strong upward motion in the sky.

This cloud is extremely similar to it's Cumulus cousin, though is more  vertically developed vs horizonally. In other words, it's taller than it is wide. These towering cumulus clouds, should they continue growing, could easily turn into Cumulonimbus clouds. Even in their current stage, a brief shower could develop from a cloud like this.