Temperature will be decreasing as we climb in the troposphere.

                                                 CAS

                                          EAS     TAS

                                                                   MN

                           Altitude

 

                                                                                                At constant CAS

                                                                                                As altitude increases

                                                            Speed                           TAS & MN increase

 

Or:

CAS is a measure of dynamic pressure = ½ 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