The effect of changing the heating efficiency on the velocity profile is quite dramatic. As ηnet ranges from 0.1 to 1 (with the average solar flux), the velocity at the upper boundary increases from 2.6 km s−1 to 25 km s−1. However, the velocity does not increase linearly with stellar flux or without a bound – in the 100× case the velocity at the upper boundary is only 30 km s−1. An interesting qualitative feature of the solutions is that the sonic point moves to a lower altitude with increasing heating efficiency or stellar flux. With ηnet = 0.1 the isothermal sonic point is located above the upper boundary whereas with ηnet = 1 it is located at 4Rp. This behavior is related to the temperature gradient and it is discussed further in Section 3.1.3. Basically the sonic point, when it exists, moves further from the planet as the high altitude heating rate decreases.
heating efficiency
ηnet
from 0.1 to 1
upper boundary
velocity
increases from 2.6 km s−1 to 25 km s−1
km s−1
case
100×
×
upper boundary
velocity
30 km s−1
km s−1
heating efficiency
ηnet
0.1
ηnet
1
isothermal sonic point
located
4Rp
Rp