28 February 2009
I have wanted to write this post for some time now. It is basically a list of things you know are true, but aren’t. You may very well know most of them, but I’d wager there will be at least one that you are surprised about.
Fact: The hottest layer of the atmosphere is the Mesosphere.
Not really true, if you use the average Joe’s definition of hot!
Temps. in the Mesosphere approach 600C. This is true. However, there are so very few molecules of air at that altitude, your hand would freeze instantly if you took off the glove of your space suit. Actually it would freeze, while your blood boiled. As far as the feeling of warmth, the Troposphere is the warmest layer of the atmosphere. The bottom 10 miles or so. The scientific definition of temperature is the average kinetic energy, of the molecules. Using that definition, the Mesosphere wins out. Even though it would feel very cold!
Fact: Clouds act like a blanket to keep the temperature warmer than on clear nights.
Nope, not so. The clouds do not “hold the heat in”. They absorb the heat, and radiate their own heat in all directions. Every object, that has a temperature, radiates electromagnetic waves. The hotter the temperature, the higher the frequency of the radiation. The sun is 6,000 degrees C, and radiates almost all of it’s light in the part of the spectrum we call visible light.
The Earth is about 15C , and radiates most of it’s energy in the Infrared wavelengths. Both are still light. Radio waves, from your favourite FM station, are light as well. We humans can only see a small portion of the electromagnetic spectrum. This IR radiation is why I can show satellite images of the weather on TV at night.
If your camping, and you sleep under a tree, you will escape most of the dew compared to your buddies, who slept right out under the stars. The tree did not catch the dew, it just radiated energy to the ground around you, and kept it warmer. Warmer ground, less dew! The same affect applies to your car windows on a frosty morning. Have you noticed, there is a lot more frost on your wind screen, than on the side windows. You can thank the radiation from nearby bushes, and trees, and walls for that!
Fact: The Wind Chill is how cold it feels, and the Heat index is how hot it feels.
I have written about this before in this space. Neither is true. The wind chill, and heat index are measures of your body’s rate of heat loss. You lose heat much faster in a breeze, than in calm air. The heat index measures the ability of the body to cool you by sweating. In a more humid airmass, water will evaporate slower. The cooling affect will be less.
Fact: The more powerful the weather radar, the farther it can “see”.
TV News promotions are probably responsible for this belief. TV stations love to say “We have the most powerful radar around!”. Actually, power is important, up to a point. The radar beam travels in nearly a straight line from the transmitter. The Earth curves away beneath the beam. So, beyond a certain distance, you’re just sending all that power into outer space!
We typically run our Radar at an elevation of 0.8 degrees above the horizon. Because of the curvature of the Earth, the beam is over 3 kilometers high, when I look at a thunderstorm 150 miles away! A shower at 1,500 meters is below the beam, and not visible.
To see a storm on radar, more than 300 miles away, it would have to be over 15 KM tall. Well into the stratosphere. I once spotted on radar, a very severe storm over Omaha Nebraska, from Tulsa, Oklahoma. That is about the limit. To spot the circulation around a tornado, you need to be rather close. Only a strong tornado could be seen more than 150 km away on a radar. A weak one is ideally within 50 km.
Fact: The Hiroshima Atom Bomb was tested in New Mexico
The bomb dropped on Nagasaki was tested in New Mexico, at the Trinity test site. The bomb that was dropped on Hiroshima, was a bomb that used Uranium 235. The difficulty in making it was getting the U235, from U238. The Physics was understood well, and the Manhattan Project scientists expected it would work. It did.
The bomb that was tested, was a bomb that split atoms of Plutonium. Plutonium is easy to get, but very difficult to make into a bomb. A sphere of it has to be crushed to get nuclear fission. Only three, or four countries on Earth, are thought to have the technical ability to do it.
Fact: Plutonium is the most toxic substance known to Man.
Horse hockey. Even Homer Simpson knows that.
You can hold it in your hand. As long as you do not breathe in tiny particles of it, you are not likely to be harmed. However, I would suggest you not stick a chunk in your back pocket, and walk around in the same jeans for a month. There is no real risk of you getting it to explode. See above!
Fact: Relativity, Climate Change, Evolution, Landing on the Moon (Insert your conspiracy here) is just a theory, and has not been proven.
Science never proves anything. To be a theory it MUST be falsifiable. In other words, it must be possible to do an experiment, that COULD prove it wrong. This is the difference between a belief, and a scientific theory. In Science, theories OUTRANK laws. Oh, and so far, no one has yet been able to falsify any of the above. Actually, nearly every experiment done has made the theories even more solid.
To which Einstein might reply:
Fact: It can be too cold to snow.
It can be too cold to snow a lot. It cannot be to cold to snow some.
As air gets colder, it can hold less moisture. This is why the Antarctic is the greatest desert on Earth. It’s drier in many places than the Sahara! Climate change is expected to cause more snow in polar regions, not less. Now you know why. (warmer air means it can snow more)
Fact: Richard P. Feynman was smarter than (Insert any name here)
This one is a trick, because he was!