0 Members and 1 Guest are viewing this topic.
I'm not too impressed by the statement"Therefore, a cloud should "weigh" less than the air it is displacing. "in the first link. If it weighed less than the air it displaces, it would float upwards! It must weigh the same (have the same density) if it stays at the same height. Their reasoning is too simplified.
There is another bit of folklore which is misleading about dryness of air. It is often said that "warm air can hold more water than cool air". Whilst this may appear to be the reason for what we observe, the real explanation is that the vapor pressure of water increases with temperature so more water will appear in the form of vapor when it is warm than when it is cold. The same pressure of water vapor could be measured if you did the experiment in an evacuated bell jar as the 'partial pressure of water in atmospheric air at the same temperature. It's the water that's doing it - not the 'air'.
Jeff Thompson asked the Naked Scientists:According to my barometer, as the atmospheric air pressure increases from 29 to 31 psi,.... Please explain.What do you think?
PaulVery succinct little article, explaining things as they 'actually are'.
...UK Science Education claims to be telling kids "How Science Works", these days. Why not do just that? Possibly because it might involve some self education for a host of people whose job it is to know and to teach it.
PaulWhat is on the curriculum is thought to be appropriate for age and level of ability - by educationists and politicians.However, what is taught depends largely on the knowledge and ability of the teachers and the grasp of Science which the course inventors happen to have - it can't be better than that, can it? Have you read a modern Key Stage 3 text book recently and looked at it 'as if' by a child?....
"Heat rises", "air is like a sponge", "Electicity and water don't mix" etc.; they all get told to kids.Is it fair?