Q: What makes snowflakes fall in an assortment of shapes? Anonymous A: Snowflakes are actually the random grouping of individual tiny ice crystals that have collected in a group. However, the randomness just ends with this grouping. It starts with the formation of these individual tiny ice crystals. When cold air becomes super saturated, invisible water vapor will change into these ice crystals through the process of deposition (much like the ice crystals of frost that form on cold ground). These ice crystals actually will have different shapes depending on the temperature of the air in which they are forming. Some are plates, some are columns, others look like mini snowflakes and are called dendrites. When you take into account that a cloud can have many types of ice crystals and that they can come together in many different ways, it’s easy to see that they can form in an infinite amount of shapes.
Q: I was told that “fish scale” or “mackerel” clouds mean that rain is on the way. Is this true and why? Beth
A: The old saying goes like this: “Mackerel sky, mackerel sky. Never long wet and never long dry.”
This is one of those old weather proverbs that actually have a little truth behind it. Altocumulus clouds are puffy clouds that form in the midlevels of the atmosphere. They can look like fish scales, and it is from these clouds that we get the mackerel sky. Altocumulus clouds indicate moisture and instability in the middle layers of the atmosphere. These clouds often precede storm systems and fronts. The lack of lower level clouds indicates a dry and/or stable lower atmosphere. If the lower atmosphere moistens or becomes more unstable, the presence of altocumulus indicates that showers or thunderstorms are a strong possibility. Therefore, these clouds can mean that rain is not too far away.
However, it’s one of those sayings that doesn’t always work. If the air near the ground stays dry, rain will not be coming anytime soon.
Q: On Feb. 8, there was a gorgeous show of frost on the trees and bushes. There was some fog that burned off. Was this the fog that accumulated ice on them? Bernie
A: You are correct in the fact that fog can leave a pretty layer of ice on trees and bushes.
A fog is actually caused by tiny droplets of water suspended in the air. If temperatures are below freezing, these droplets of water can still be liquid supercooled water.
Water does need some sort of nucleus to freeze upon in most situations. In this case, the supercooled water does not freeze until it makes contact with objects such as trees, bushes and even roadways.
In fact, extreme caution should be used when driving in fog with temperatures below freezing because it can cause a thin layer of ice on the roads.
After the fog burns off, there can be a beautiful show of ice glistening on objects such as trees and bushes. In this case, however, it was more than fog. It was freezing rain that coated the branches that night before the fog formed. This left a thick glaze of ice on many surfaces.
If you have a question about the weather, you can write to Joe Murgo at 5000 Sixth Ave., Altoona, PA 16602 or e-mail Murgo@wtajtv.com. Some questions will be answered here and all of the questions will be entered in a contest to be shown on 10 News at 5 p.m.