Hi all, I'm still brand new to the site and am still trying to get my head round just about everything on here. Something that has got me really confused is the use of hpa. I understand that hpa (hectopascal) is a measure of air pressure and hope I'm right in thinking that this pressure decreases the further up you go in the atmosphere and the air becomes thinner. So am I right in thinking that the 1000hpa wind vectors I see on the chart are low level winds when compared with the 300hpa wind vectors? The 300hpa vectors are a lot more uniform on the charts and so does this mean the winds high up in the atmosphere are a lot more settled (I always assumed it was a lot more turbulent up there). Also, in laymans terms, how do you use these wind vectors? If I see, as at the moment, a big bank of snow, how do I know whether it is following the course of the 300hpa vetors or the 1000hpa vectors. I know this is probably a question that will have so many other variables attached to it but just a rough idea would be much appreciated.