1. An isobar is an imaginary line drawn through the places which have equal atmospheric pressure reduced to sea level. 
2. The isobars form layered rings on the weather map.
3. The closer the layers of the rings are to eachother, the lower the air pressure in that area is. The further apart they are the higher the air pressure.
4. The closer the isobars are, the stronger the wind is.
5. The air pressure is also depicted by letters. In an area where the isobars show that it has a high pressure, a 'H' will be in the the centre circle. If there is low air pressure there will be an 'L'.
6. Air pressure is the density of air molecules. High air pressure is heaps of air molecules close together. Low air pressure is when they are far apart. When the air pressure changes from high to low, wind is created.