If we have normal conditions; temperature decreasing as we climb in the troposphere.
CAS
EAS TAS
MN
Altitude
At constant CAS
As altitude increases
Speed MN increases
Or:
CAS is a measure of dynamic pressure = ½ρV2
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