Friday, 5 April 2013
528 Line Down Across Kent -unseasonably cold weather indicator
The isobars and fronts of standard weather charts are not adequate in showing atmospheric temperature. It remains criminally cold across southern England; snow has no place in Kent in April. This cold weather event can be seen more clearly on an atmospheric thickness chart. Pressure is caused the mass of air above. The same mass of air would be of greater vertical extent (I.e. THICK) if warm or lesser (ie THIN) if cold. It turns out that an atmosphere which has a thickness of 5280 geopotential metres (measured from the 500mb level to the 1000mb level) gives a 50% chance of snow at sea level. Thickness charts like the one attached give an excellent snapshot of the temperature of the air across a region. With old fashioned meteorologists paying great attention to the position of the '528'.