Definition
Thickness refers to the vertical distance between two pressure surfaces (isobars).
The thickness of a layer is related to the mean virtual temperature (Tv) according to the formula:
Where:
- ΔZ = thickness (m)
- Rd = gas constant for dry air
= mean virtual temperature for the layer
- p1 = pressure at the bottom of the layer
- p2 = pressure at the top of the layer
- g = gravitational acceleration
Note that for a given pair of pressures, the thickness is proportional to the mean virtual temperature (Tv) in the layer. The 1000:500 hPa thickness chart is perhaps the most common and is typically plotted with 60-meter contours. In this case, each contour reflects a mean virtual temperature change of 3°C.