Bright

In a matter of days, on the 5th of July at 14:44 GMT to be precise, the Earth will be at its furthest from the Sun. Yet, in the Northern hemisphere, summer temperatures will be in the mid 20s Celsius. Isn’t it strange that it’s hotter in the Northern hemisphere when the Earth is actually furthest from the Sun? Shouldn’t it be cooler instead? Had things been plain and simple, that’s how you would expect the temperature to vary: the closer one is to the Sun, the warmer one should be. Think of the scorching temperatures on Mercury and the icy conditions on far-flung Pluto (which, by the way, isn’t one of the planets of the Solar System but I’m simply using it as an example of a distant object from the Sun). But things aren’t that plain – though they can still be simple – and therefore it is the tilt of the Earth that determines the season, not its distance from the Sun. Had the Earth not tilted at 23.5 degrees from the vertical, the seasons would have been pretty much none-existing. A minimal and boring hot/cold variation would have prevailed throughout the year depending on how far the Earth was from the Sun as opposed to how much it was leaning off its axis of rotation.

Big ball of fire...

Big ball of fire…

So how much of a difference is there really in the amount of warmth we get depending on how close or far the Earth is from the Sun? It’s roughly 7%. Not significant enough for all practical purposes. Yet the amount of solar energy we get on a daily basis is enough to meet the energy requirement for a whole year! The trouble is, we can’t quite harness that near inexhaustible source of energy. We do have solar cells and solar water heaters and stuff like that but their efficiency is what makes them not fully economically viable solutions. So far we can capture more of the Sun’s heat than generate electricity from its light. But the trouble with solar panels (compared to photovoltaic cells) is that you need a large, very large surface area to capture the heat since the solar heat is more spread out or diffused than the sunlight. You need vast fields of mirrors to redirect the radiation from the sun onto a tank of water to produce steam in order to power a generator and thus produce electricity. Building and maintaining such a huge installation has costs running into the billions of dollars, making the whole project not so financially appealing. The problem with photovoltaic cells, which produces electricity directly from sunlight (thus bypassing the steam phase), is that their efficiency is still unsatisfactory. The idea of a ecofriendly planet running off energy from the Sun is still in our wish-list. We have yet to improve on our technology to harness this bottomless reservoir of solar energy.

I reckon the Earth will have completed a few dozens of trips around the Sun before we are fully reliable on solar energy. Until then we still need to dig in the reserves from long dead organic materials and pump away those crude oils and shale gases. Even nuclear energy has its downside. Fukushima is but a recent reminder of such dangers. But, as goes the song, always look on the bright side of life. We have teams of scientists and engineers devising ever sophisticated ways to bring the best to the world. Without them we would still be in the dark ages…

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One thought on “Bright

  1. Pingback: Lady in Red | electrolights

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