نحن قوم أعزنا الله بالإسلام ، فهما طلبنا العزة بغيره ، أذلنا الله

We are the people whom Allah honoured through Islam, so whenever we seek honour other than it, Allah will disgrace us.

The blog is under slow transition to http://specifichumidity.wordpress.com

Tuesday, March 14, 2006


I have just finished reading this article. It talks about ice an how we are losing more and more ice in the Arctic.

Why do we need them? Is Europe not cold enough?

Ice is one of few things that can actually reflect radiation from the sun. It's coefficient of reflection is 0.8 (that is 80%). As the surface of ice absorbs radiation, the absorptivity drops. This will prevent more ice from melting. (Imagine trying to dissolve more and more sugar in water). However, if there is enough energy to maintain heat conduction, ice can definitely melt.

Other materials tend to simply absorb radiation, expecially water. 2/3 of the Earth's surface is covered by water. Is it not enough absorption already? For this reason, Ice in the Poles are really crucial in stabilising the temperature of the Earth.

The main problem is, there can hardly be any ice re-formation. Ice can reflect 80% of radiation. But once it melts, it will become water, which will absorp almost 100% of the energy (compare 80% reflection to 0%). Once the absorption process stars, it will keep on warming the water, hence ice re-formation is quite impossible.

Home Experiment:
Try melt a block of ice in a microwave. You will find that ice hardly melt inside microwave, simply because it does not absorb the microwave radiation. Only the first few micrometres will be warmed. but it should not be warm enough for the ice to melt immediately, considering the amount of energy being radiated onto it.

If you use thaw function in your microwave, please realise that the microwave is automatically switched on and off (listen to the sound). This is because, the time interval is required to allow heat conduction, so that heat can penetrate deep into the core.


Post a Comment

<< Home