13 June 2009

Rain Drops and Mislabeled Faucets

Posted by Dan Satterfield

There is a small group of people, whose war on science mantra, is that the truth cannot get published in the peer reviewed journals. It’s one of these conspiracy theories, like the ones that say we did not land on the moon, or Roswell UFO’s.

It’s ridiculous of course, because the quickest way to get famous in the science world is to write a paper that blows an accepted theory out of the water! Let me tell you about two recent examples of  people who did just that. One of them is happening right now! It’s in Atmospheric Science too.

The first has to do with expansion of the Universe. The average guy on the street knows the Universe is expanding, excluding the ones Jay Leno runs into. (American joke, for those of you in other exotic lands, that I long to visit) What most people do not know, is that this rate of expansion is INCREASING. This goes against what everyone thought 20 years ago. It was widely assumed that the rate of expansion was slowly decreasing and at an infinite time in the future, it would stop.

Thanks to XKCD.COM for this hilarious and true explanation of the electromagnetic spectrum!

Thanks to XKCD.COM for this hilarious and true (well mostly) explanation of the electromagnetic spectrum! Click for full size.

The Hubble Deep Field. The Galaxies are flying apart more rapidly - but why??

The Hubble Deep Field. The Galaxies are flying apart more rapidly - but why?

What’s causing it?


The force is called dark energy because it cannot be seen or explained, but it must be there. One of the Astronomers on the team who discovered this increasing expansion is Alex Filippenko of U.Cal. Berkeley.

I’ve written about his fabulous course on Astronomy for non science majors, here before. You can view the ENTIRE series of lectures online and you will really enjoy it. TRUST ME. (first lecture audio is a bit hot).

This discovery has made he and his team very well known in the science world and even among the public at large. You have probably heard or read something about dark energy and the expanding universe already!

Now, here is an interesting tidbit mentioned on one of his lectures. In the real world of Physics, cool things give off heat in the infra red region of the electromagnetic spectrum. Satellites I look at daily, are usually IR images. They are detecting light that our eyes cannot see. If the clouds were to suddenly heat up to 500 degrees, we would not need an IR satellite sensor to see them at night. They would glow red!

Just because we cannot see it with our eyes, does not mean that electromagnetic radiation is not light. It is no different than radio waves, or x rays. They are ALL light. Some animals see ultra-violet and infrared light,we Homo sapiens cannot.

Same thing with stars. Cool stars are red, and hotter stars like our sun are whiter, while giant very hot stars are Blue. So in the real universe, red is cold and blue is hot.

Picture 1

5 Day Forecast from KIRO TV Seattle web site. Notice the cool night time temps. are labeled blue.


We TV Meteorologists are guilty of this too!

Look at the 7 day forecast for Seattle from KIRO TV. (Mine uses white numbers, but I have used blue in the past, so I am guilty as well!

Dr. Filippenko collects these mislabeled images and he has a good discussion of it in the 2007 series of online lectures. I won’t tell you which one, because watching them all will fill your mind with the wonder of the universe.

The other example of blowing out a long accepted theory also has to with labels and pictures not imitating physical reality. In this case it is rain drops! They are always drawn incorrectly!

A little background first. Galileo was among the first to realize that the weight of something has nothing to with how fast it falls. Drop an anvil off a tall building and it will speed up by 9.81 meters per second, every second. A feather will not.

Obviously, because of wind resistance. This was illustrated by one of the Apollo Astronauts, who dropped a hammer and feather, on the airless moon. Galileo was proved right!

On earth, a falling object reaches what is called terminal velocity. This speed is a balance between the force of gravity pulling down and the wind resistance pushing up. If you jump from an airplane at 1,000 meters or 5,000 meters, without a parachute, you will still hit the ground at a little over 100 mph. You will of course, be just as dead in either case.

Do raindrops look like this??

Do raindrops look like this?? (dan's pic)

It’s long been known that raindrops fall at a terminal velocity with larger raindrops falling faster than smaller ones. As a rain drop gets larger it has more mass, while increasing much less in area, so it’s momentum increases faster than the increasing air resistance. This has been proven in at least a half dozen studies. I was taught this many years ago as an undergrad at Okla. University. Every Meteorologist knows this. Apparently, we are all wrong too!

Three scientists have just published a paper that shows conclusive evidence that some rain drops fall an order of magnitude faster than predicted! These “super terminal” drops are thought to form from the break up of large drops in collisions as they fall.


Falling raindrops Look more like squished buns! My wife took the bun back!

This has important implications in using radar to estimate rainfall totals. Increasingly Doppler Radar and the new Dual Polarimetric Radars, are being used to measure rainfall in remote areas for hydrological and short fused flood warning purposes.

Nearly all of the NOAA Weather radars in the USA will be upgraded to dual pole capability soon. The TV station I work for was the first station in the world to begin using this technology. We call the radar ARMOR. That stands for Advanced Radar for Meteor. Operations and Research.

This discovery promises to make these rainfall estimations more accurate. Our radar is a joint project with the U. of Alabama at Huntsville. We use it to monitor storms, and they for research. Dr. Walt Petersen is the lead scientist and is working on several studies for NASA, and this discovery might just be beneficial.

While Alex Fillipenko has his hot and cold issue, I have a rain drop issue. Most people think they look like – well, you know, rain drops. They don’t! Falling drops look more like hamburger buns, well close anyhow, and definitely not like the image I took of my wife holding the eye dropper!

So Doctor Filippenko, if you read this, I promise to never use blue numbers for lows on weather maps, but you have to draw any raindrops like squashed hamburger buns!