Thickness



1000-500 mb Thickness

Why would you want to know about the 1000-500 mb thickness? For one, nearly all the weather that takes place in the world occurs between 1000 and 500mb, which is basically what the 1000-500 mb thickness describes. Also, it is a good forecasting tool because it shows us the average temperature of the air in between these given levels.

In order to understand thickness, you must first understand what a constant pressure surface is, so let’s define it. Constant Pressure Surface- is any layer in the atmosphere where the pressure is the same. For our purposes, we will be looking at the 1000 mb constant pressure surface and the 500 mb constant pressure surface.

We can now delve into thickness. Thickness is defined as simply the distance between two constant pressure surfaces. For the 1000-500 mb thickness, it is simply the distance between the 1000 mb constant pressure surface and the 500 mb constant pressure surface.

When looking at the upper right hand panel of the computer model maps, the 1000-500 mb thickness is represented by dashed contour lines. They are usually labeled with numbers in the 500’s, and they vary by 6 from line to line. These numbers in the 500’s represents thickness in decameters. The best way to explain this is to use an example. If you're gazing at the upper right hand panel and see a 546 labeled line, this means that the thickness is 546 decameters. If you want to look at these numbers in meters simply add a zero to them. Using our example of 546 decameters, add a 0 to this and you would get 5460 m.