Wednesday, April 17, 2013

Asteroid Warning Light

Just as there are certain streets I shouldn't walk down, there are certain parts of the Internet to which I should know better than to go, but sometimes I take a wrong turn. As Randall Munroe lamented, "Someone is wrong on the Internet."

I wasn't brave enough to seek out the site the question appeared on to look at the answers given to this individual, and I know it's not fair to call them out. I have no idea how old they are nor what opportunity they have had to learn information seeking and critical thinking strategies. At least they asked.

When I taught meteorology in ground school, I used to go around the room and have everyone name a place water was found in the environment. They were usually enough people trying to be clever that the resulting list included ponds, lakes, rivers, oceans, people, animals, martinis, glaciers, the air itself, clouds, fog and so on. We'd go through the list and discuss the phase of water present in each case. Almost everyone started the class thinking that clouds were composed of water vapour. A lot of them knew that water vapour was an invisible gas in the air around them, but for some reason they rarely saw this at odds with their ability to see clouds.

While there are "clouds of gas," unqualified "clouds" are made of water, in the form of liquid droplets and/or ice crystals. The higher the altitude, the colder the air and the greater the proportion of ice to water in the cloud. The droplets may circulate upward and downward within a cloud, meaning that liquid water may freeze and ice may melt, but more dangerously, liquid water may be cooled below zero celsius yet not immediately freeze. This is dangerous because supercooled liquids tend to freeze on contact with a surface, such as an airplane flying through them. There's a readout on my dashboard giving the outside air temperature, and when that temperature is between about +4 and -15C, an amber light turns on, warning me that I'm in the icing zone. Any visible liquid moisture (clouds, fog, rain) at that altitude could be supercooled, and turn to ice on my airplane.

I don't have an asteroid warning light. Maybe on the Starship Enterprise.


D.B. said...

What kind of temp warning system is that? A warning light would be a nice feature (even better if it just turned on the darn pitot heat for me). Of course, not being in Canada I don't see it as often as you.

I've twice seen icing on my plane. The first time was at 11,000 over the mountains of New Mexico, and I just wasn't expecting it (had never seen it before - because I live in Texas). The second time, a few weeks ago, over central Arkansas descending through a layer at 3,000 ft. That time I was ready and had the heat on. But a light would really help with situational awareness.

Sarah said...

It's tough to tell, on the internet, if a post or poster is really as dumb as they appear or just trying to be funny. Kind of a "Poe's Law" for stupidity.

majroj said...

Our local pioneer aero traffic reporter, "Commander Bill" Eveland, would give extremely local, precise, correct and timely reports and accurate forecasts when he was up, which actually angered the weather lady on their sister TV station (he fed his reports to one AM, at least one FM, and one TV station). Fliers are potentially the best weather people.

Do you have any recommended books, URL's or etc for learning more about pragmatic useful weather forecasting?

majroj said...

..and never fly through an Oort Cloud.
click here