Thank you all for the replies and clearing a few things up.
One thing, if for example I am doing something more complicated like doing some formula, does the arduino use the RAM to store intermediate results (for example if I have to do ((a+b)/(c+d))) would it store lets say a+b in RAM once calculated while it is calculating c+d?) What I am getting at is, would these types of operations use more RAM or would they be independent.
Its just that, as well as storing wind speed and direction, I need to write code to measure temperature, pressure, rainfall and humidity. I was just a bit worried that possibly I may run out of resources on the Arduino when I finally put everythimg together.
Thanks again.