weather [wind] [3] [information over pictures]

Have you heard of a scientist called Isaac Newton? He named a force called gravity. Gravity is a force of attraction between any two masses. In this case the air and the Earth.	When gravity acts on the air, the air exerts a force upon the Earth called atmospheric or air pressure. A millibar is the unit that is used to record that atmospheric or air pressure.	Here you can see that in terms of the weather. High Pressure [H] and Low Pressure [L].
These are also know as cyclones and anticyclones. You will need to know about these ready for the weather forcasting section.	Here is an animation that shows you how a barometer works. The increase or decrease in air pressure moves the needle around the dial.	Here is a real barometer. The dial goes from 28 millibars [stormy weather] to 29 millibars [rainy weather] to 30 millibars [fair weather] and 31 millibars [very dry weather].

Look at all of the pictures in turn. As you hover over each one a blue screen appears with an explanation of what the picture shows. Important words are coloured. If you are certain that you know about the picture click on it and it will disappear. As you go through all of the pictures you will get rid of all those which you know about and be only left with those you may be unsure of. In some cases you may get rid of all of the pictures in which case you are ready to move on to other activities which will test your knowledge on that particular topic.