Thoughts

My presentation went very well. The church group was full of kind, educated, and passionate people. It was nice to have an audience that wasn’t full of high school students who thought science was boring!

After the presentation, a woman in the group shared something with me that she found at a conference in Australia just before the Copenhagen summit. I liked it so much that I thought I’d share it here, with her permission.

If the earth
were only a few feet in
diameter, floating a few feet above
a field somewhere, people would come
from everywhere to marvel at it. People would
walk around it marvelling at its big pools of water,
its little pools and the water flowing between the pools.
People would marvel at the bumps on it, and the holes in it,
and they would marvel at the very thin layer of gas surrounding
it and the water suspended in the gas. The people would
marvel at all the creatures walking around the surface of the ball
and at the creatures in the water. The people would declare it
as sacred because it was the only one and they would protect
it so that it would not be hurt. The ball would be the
greatest wonder known and people around would come to
pray to it, to be healed, to gain knowledge, to know
beauty and to wonder how it could be. People
would love it and defend it with their lives
because they would somehow know that
their lives, their own roundness, could
be nothing without it. If the
Earth were only a few
feet in diameter.

-Joe Miller

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The Energy Budget

I’ve decided to take this blog more in the direction of communicating science – there are only so many sociological musings to come up with. This is the first of many planned posts explaining basic climate science so people have better context for what they read in the newspaper.

Every post is a work in progress, and will be continuously edited when necessary, so please leave comments with suggestions on how to improve the accuracy or clarity. Enjoy!

What determines the temperature of the Earth?

The temperature in your backyard, the warmth of the equator, the frigid polar regions, the average global temperature for the whole planet…..they might seem like very different things to measure, but they’re all caused by the same process. It all comes back to energy.

This energy comes from the Sun, but it’s not as simple as a single transfer. Remember, at any time of the day or night, the Sun is shining on some part of the Earth. That energy can’t just stay on our planet, otherwise it would keep building up and up and we would fry after a couple of weeks.

Therefore, incoming energy from the Sun has to be balanced by outgoing energy from the Earth for the planet’s temperature to stay relatively constant. So when the Sun’s rays hit the ground, as a mixture of light, infrared, and UV radiation, the Earth absorbs the energy. Then it converts it to all to infrared radiation, which we perceive as heat when it hits us, and releases it upward.

All objects perform this absorption and emission when they are hit with radiation. If they receive enough energy, they can release some of it in the form of light – think of how a stove element glows when it’s turned on. However, the energy hitting the Earth is nowhere near this level, so it all comes out as infrared.

It is this emission of infrared radiation that determines the temperature of the Earth. The second step, not the first, is the important one, the one that we actually feel and experience. So on a hot summer’s day, it isn’t actually energy coming down from the Sun that’s making the air warm. It’s energy coming up from the Earth.

The air doesn’t warm up instantly, either – there’s a bit of a lag. This allows warm air to be transported away from the Equator and towards the poles, in the global circulation system of wind currents. Without this lag time, many regions of our world would have far more extreme temperatures.

Additionally, not all the radiation the Sun sends down gets absorbed by the Earth. Some of it is bounced back by clouds, which is why sunny days tend to be warmer than cloudy days. Some of it reaches the surface of the planet, but is bounced back too, before it’s even absorbed. This reflection of energy is particularly common when the surface is light in colour. That’s why it seems so bright outside after a snowstorm – because the snow is bouncing the energy back up as light, instead of absorbing it and releasing it upward as heat. It also explains why dark concrete, which absorbs almost all the radiation that hits it, is so much warmer than a light-coloured deck.

The amount of energy that the Sun sends down to us is greater than the amount that the surface of the Earth actually absorbs. However, the amount absorbed has to be equal to the amount released, and the amount released is what we witness as the temperature outside.