I had a query at work today.

I am told that Flight minima [such as Minimum Decision ] Heights are
adjusted to take account of the temperature relative to the 'base station'
temperature when looking at QNHs [Pressure at sea level]

So in the case of Heathrow, which has a recorded standard temperature oif
+15c apparently, any change in temperature from that, needs manual
adjustment to find the 'true height' given a pressure setting.

I am told that a true height of 280ft would be adjusted by around 30ft if
the temperature was zero, to make an indicated height of 310ft.

As the temperatures go down, the indicated height goes up i.e the actual
height goes down
and as the temps do up, the indicated heights goes down but the actual
heights go up.

I thought, as the temperature goes up, the pressure goes down i.e 'Heat
Low', so for a given pressure setting, would your height go down which seems
to contracdict the above!

Any help anyone!

Phil