Below the tropopause temperature decreases with altitude.
CAS
EAS TAS
MN
Altitude
At constant CAS
As altitude increases
Speed TAS
& MN increase
Or:
CAS is a measure of dynamic pressure = ˝ ρV2
Where ρ = air density (decreasing in climb) and V = TAS (increasing to keep CAS constant)
LSS is decreasing as temperature decreases.
MN = TAS/LSS = Increasing/Decreasing = Increasing