200yards

[Gary C]

Merchant.

My congratulations on a well reasoned argument , and I concede happily. My training as a surveyor was 30 years ago time has let me remember some points but let me forget others.

SoS varies with altitude, that is a simple fact.
SoS varies with pressure and density, that is a fact.

However I forgot that the relationship between pressure and density is opposite and equal, therefore as one effects the S0S with altitude the other cancels it out. Therefore, as you said, these factors do not come into play.

However the original assertion with I remember well is that SoS varies with altitude is correct due to temperature and humidity calculations. In Europe, IIRC, temp declines 3 degrees per 1000 feet and humidity changes also. This means that, in theory, given constant humidity and temp S0S will remain constant with altitude, while in practice I know of no geographical region where there phenomena could occur

Many thanks, I've enjoyed re-reading this and it's brought back some memories. My thirst for knowledge quenched, I'm off to surf for porn