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Global Cooling in Telegraph

The Temperature of the Earth

The following calculation assumes that the energy into the Earth system and the energy out are not affected by the atmospheric gasses. When the system is in equilibrium, that is neither warming nor cooling, Energy In must equal Energy Out.

Energy In

Energy enters the Earth system from the sun mainly in the form of visible light. This solar flux is represented by the letter L. The value is 1361 Watts per square metre (W/m²). About 30% of the light from the sun is reflected out of the Earth system, mainly by clouds and ice. The reflectivity of the planet is called the albedo and is represented by the letter α.

Each square metre then absorbs energy from the sun according to the following formula:
L(1 – α)

We are interested in the total energy absorbed. The solar flux varies over the surface of the Earth, strongest at the equator where the surface is perpendicular to the incoming light and weakest at the poles where the surface is at a large angle to the sun’s rays. Adding up all of these variable amounts is tricky but there is a simple method to calculate it. The light waves from the sun are parallel to each other and the Earth intercepts them and casts a shadow. This shadow is a circle which has a simple formula - πr². So the formula for the total energy from the Sun absorbed by the earth is:
L(1 – α) πr²

Energy out

The formula for the energy that is radiated away from the surface is:
ϵσT⁴ 4 πr²
ϵ is emissivity, how close the source is to a black body (0 not a back body to 1 a black body), σ the Stefan-Boltzman constant, 5.67 X 10^-8 (Watts/square metre), T⁴ is temperature in Kelvin raised to the fourth power, 4πr² is area of a sphere.
If the system is in equilibrium Energy In equals Energy Out
So
L(1 – α) πr² = ϵσT⁴ 4 πr²

Calculate Temperature, ie solve for T

πr² appears on both sides so it can be cancelled

So
L(1 – α) = 4 ϵσT⁴



With L = 1361 W/m² α = 0.3 σ = 5.67 X 10^-8 and ϵ = 1 (given that Earth is relatively close to being a black body)
T = 254.5 K,
(K is degrees Kelvin. The Kelvin Scale starts at absolute zero ie -273⁰ Celsius. Note Kelvin temperatures are indicated by K, and do not by convention use a degree (⁰) sign.)

Consequently 254.5 K equals -18.5⁰ C

Given that the global temperature is about 15⁰ C, according to this calculation the planet should be about 33⁰ C below current temperatures.

This calculation gives a very incorrect answer because it ignores the effect of Greenhouse Gasses.

The Discovery of Infrared by William Hershel

The Discovery of Infrared by William Hershel

Before I started researching this topic I was only aware of Herschel as the discoverer of the planet Uranus in 1781.

It turns out that he made at least one other important discovery, that if infrared light, in 1800.

Herschel's discovery is described at this website in the following way:

He was interested in learning how much heat passed through the different colored filters he used to observe the Sun and noticed that filters of different colors seemed to pass different levels of heat. Herschel thought that the colors themselves might contain different levels of heat, so he devised a clever experiment to investigate his hypothesis.

Herschel directed sunlight through a glass prism to create a spectrum - the "rainbow" created when light is divided into its colors - and measured the temperature of each color. He used three thermometers with blackened bulbs (to better absorb the heat) and, for each color of the spectrum, placed one bulb in a visible color while the other two were placed beyond the spectrum as control samples. As he measured the temperatures of the violet, blue, green, yellow, orange and red light, he noticed that all of the colors had temperatures higher than the controls and that the temperature of the colors increased from the violet to the red part of the spectrum. After noticing this pattern, Herschel decided to measure the temperature just beyond the red portion of the spectrum in a region apparently devoid of sunlight. To his surprise, he found that this region had the highest temperature of all.

Herschel performed further experiments on what he called "calorific rays" (derived from the Latin word for 'heat') beyond the red portion of the spectrum. He found that they were reflected, refracted, absorbed and transmitted just like visible light. What Sir William had discovered was a form of light (or radiation) beyond red light. These "calorific rays" were later renamed infrared rays or infrared radiation (the prefix infra means `below'). Herschel's experiment was important not only because it led to the discovery of infrared light, but also because it was the first time that someone showed that there were forms of light that we cannot see with our eyes.

The video below was produced by FLIR Systems, makers of infrared thermal imaging systems. It begins by describing Herschel's experiment and infrared light in general, before describing the use of thermal imaging systems in the modern world.

Over the next century or so the rest of the electromagnetic spectrum was discovered.

The diagram below shows where light and infra red fit into the the electromagnetic spectrum. Infra red has a wavelength between 0.7 and 300 micrometres. A micrometre (micrometer for Americans. The symbol for a micrometre is µm.

Did Julia Gillard Lie?

I first posted this on a different blog in 2011. I am reposting it as the issue of carbon pricing is becoming important again.

It is often claimed that Julia Gillard is a liar on the basis that she said before the last election that she would not introduce a Carbon Tax. The argument continues that as she is now introducing a Carbon Tax she lied. Some people have taken to calling her JuLIAR.

There are two issues to consider here:

1. What did Gillard actually say before the last election?

2. What is the nature of the legislation that is currently before the parliament?

The day before the election the Australian published an article on Gillard that can be found at this link.

Here is the direct quote from Gillard from that article:

"I don't rule out the possibility of legislating a Carbon Pollution Reduction Scheme, a market-based mechanism," she said of the next parliament. "I rule out a carbon tax."

The Carbon Pollution Reduction Scheme mentioned in the quote is the Emissions Trading Scheme (ETS) that was negotiated between the Rudd Government and the then Opposition led by Malcolm Turnbull. (The Opposition kicked out Turnbull, but only by one vote, the then reneged on the agreed ETS.)

So she ruled out a Carbon Tax but not an Emissions Trading Scheme.

See this post and this post for analyses of the differences between a Carbon Tax and an Emissions Trading Scheme.

So what is the Government introducing a Carbon Tax or an Emissions Trading Scheme (ETS)?

The clear answer is that it is an ETS.

There is an interesting wrinkle though. For the first few years of the scheme it will operate somewhat like a Carbon Tax as the price per tonne of carbon released will be charged at a fixed price ($23 per tonne). There are differences though as the permits can be traded.

The reason why there will be an initial price placed on carbon emissions is to facilitate the transition to a full ETS and avoid the problems of excess permits that occurred in the early years of the European ETS.

So the simple answer to the question: did Gillard Lie, is clearly no.

She did not rule out an ETS before the election and she is now introducing an ETS to the parliament.

It is significant that the quote from Gillard came from the Australian newspaper. This is not some left of centre paper. The Australian has made its life work to destroy the Gillard Government.

Here is a link with comments by Gillard on how the price mechanism would work.

The best speech in the Federal Parliament given on the topic of Carbon Pricing was by Malcolm Turnbull. The speech can be found here.

This post emphasises the importance of checking original sources. For an interesting take on this issue see this post.

The climate policy worked out by the Multi-party committee - Government, Independents and Greens - is based on the Garnaut review, the summary of which can be found here.