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
Nope.
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!
Feynman Lives!
this is why i always criticize science students all over the world cos their facts are sometimes wrong......but for we art students, we live by the truth.
Later,
michelis
Wednesday, 26 March 2014
Scientific Facts That Are Not True
03:15
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