
                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: THURSDAY, March 9, 1995                   TAG: 9503090019
SECTION: EXTRA                    PAGE: 6   EDITION: METRO WHY THINGS ARE  
SOURCE: 
DATELINE:                                 LENGTH: Long

HE'S RIGHT, EVEN IF WIFE GETS COLD FEET

We deal in two distinct types of questions. The first type is the kind of question that only the Why staff would ever wonder, also known as a ``bad'' question. For example, the other day we were wondering if there had ever been a person who had only a sense of smell, with no other senses. We were certain that if such a person had ever existed he or she would have invented a personal odor-based language. We're still checking.

The other type of question is the type that an actual human being would find interesting, also known as a ``good'' question. It often has a practical aspect. Case in point: Gregory P., of Glen Burnie, Md., writes:

``Please help settle a dispute between my wife and me. When it's cold outside, I `warm up' the car and I turn on the heater full blast. My wife waits until the car has warmed up, then turns on the heater at medium. I think my way heats the inside of the car faster than her way. Do you know if this theory has ever been imagined or tested? I think my wife doesn't like to have the heater on full blast because it blows on her exposed or nylon-clad ankles.''

Dear Greg: Let's make a deal. You get to be the winner of the dispute, in terms of the engineering question. But then you have to promise not to blast cold air on the ankles of your wife. This issue requires both an understanding of machines and an understanding of human beings.

The car heats faster if you blast the heater from the very start. We are assured of this by John Kill, chief engineer for climate control subsystems at Ford Motor Company. In American cars, the heat comes from the engine coolant. That's right: As the coolant warms up, it warms the heater core. The heater core is like a radiator, with little metal fins. Air blows across the heater core, then onto your legs.

The coolant starts warming immediately. By running the heater full blast you maximize the heat transfer, even when things are still pretty darn cold. This will warm a car about 20 percent to 25 percent faster than if you wait until the engine is warm and then turn on the heater, Kill says.

But obviously in the meantime you have to endure the wind chill on your legs. Why endure several minutes of discomfort, and get in squabbles with your spouse, simply because you want the interior of the car to be toasty in 6 minutes instead of 8?

You could always ask your wife to ride in the back seat, however. You could pretend to be her chauffeur.

James and Marie U. of Morganza, Md., ask, ``Why are raindrops sometimes heavy, fat drops that splat across the windshield, yet other times fine, small drops that, even in a heavy rain, seem to fall lightly?''

Dear Jimmy and Marie: We've always wondered if rain has ever come down so hard that it was fatal. Because we think killed-by-rain would be a really poetic way to go.

The big hairy raindrops usually come from thunderheads, those tall cumulus clouds common in summer. The wind currents force the droplets up and down and they grow bigger and bigger, with the biggest drops being about the size of a pea, a fifth of an inch across, according to Allan Eustis, a meteorologist with the National Weather Service.

The larger the drop, the greater its terminal velocity. This is not because gravity ``pulls'' it harder. It's because air pressure has more effect on a small drop. It can't cut through the atmosphere as well.

A pea-sized drop can reach a terminal velocity of about 30 feet per second. It hits your windshield with all that force because it's big and fast, like a pro football linebacker.

The smaller drops tend to form in horizontally organized, layered clouds, without all the convection and turbulence and drama. A typical raindrop is 0.06 inches, or about one-seventeenth of an inch, across. At that size it can't go much faster than about 13 feet per second. It just pitter-patters.

Eustis points out that raindrops aren't teardrop-shaped. They have flattened bottoms, because of the air pressure.

``They kind of look like hamburger buns,'' he said.

Eustis says that if the drops are less than 0.02 inches in diameter, the precipitation is no longer considered rain. By definition it's drizzle. (Before you tell anyone it's drizzling outside, please verify the droplet diameter.)

Elaine M., of Columbus, Ohio, writes, ``Does the increasing number of plagiarism suits in popular music possibly indicate that songwriters are running out of original melodies?''

Dear Elaine: It may just indicate that the nation has too many lawyers. A second factor is that in rap music it is common to ``sample'' other songs, and that sometimes causes a fuss.

But please don't think that there are a finite number of potential songs. There's just a finite amount of talent in the business at any given moment. Styles get standardized. Songwriters lose inspiration. But there's an infinite number of possible tunes. Peter Manuel, an ethnomusicologist at the City University of New York, says, ``There's an infinite number of melodies you can make with two notes, with the element of rhythm thrown in.''

And we'd add that you can always make something sound fresh and very ``Now'' by adding a tambourine.

- Washington Post Writers Group

by CNB