The General Circulation - An Introduction to Dynamic Meteorology - page 358

This nondimensional number is the best measure of the range of validity of quasi-
geostrophic dynamics in annulus experiments. Provided that Ro T 1 the quasi-

geostrophic theory should be valid for motions in the annulus. For example, in a
typical experiment

1s − 1 H ≈ b − a ≈ 10 cm, δT ≈ 10 K, and ≈

10 − 1 .
Annulus experiments carried out over a wide range of rotation rates and temper-
ature contrasts produce results that can be classified consistently on a log-log plot
of the thermal Rossby number versus a nondimensional measure of the rotation
rate :

Thus, Ro T ≈

G ∗ − 1

a) 2 /g

≡ (b − (10.78)

Fig. 10.21 Regime diagram for Fultz's annulus experiments. (After Phillips, 1963.)