Megan Marra’s Reviews > Atmospheric Science: An Introductory Survey (International Geophysics) by John M. Wallace > Status Update

Just as in the Carnot cycle, heat is added at a high temp (in the lower troposphere) and rejected at a lower temp (higher in the troposphere)

The efficiency (eta) of the atmosphere is quite low bc the difference between the mean added and rejected temps (T1 and T2) is only a few degrees

⚠️⚡️⚠️ atmospheric motions transport E poleward and upward from a WARM SOURCE to a SLIGHTLY COLDER SINK

⚠️⚡️⚠️ In a statistical sense, the SOURCES of energy for the atmosphere are located at relatively low latitudes and low elevation, while the SINKS of energy are located at somewhat higher latitudes and higher levels where the temps are somewhat lower

The total area under the curves (avg’d net solar radiation) are identical but the SHAPES of the two curves are different. The net solar radiation (1-A)S/4 drops off by that factor of 4 between the equator and the poles. This strong latitudinal gradient is largely bc the SHARP DECREASE IN INSOLATION W LATITUDE during the winter season and the large local albedo that prevails in polar regions (icecaps+summer clouds)

Thermally driven = the wind field bears a direct relation to the horizontal heating pattern

⚠️✈️ Waves like the Kelvin-Helmholtz ones are often present within laters of moderate and severe clear air turbulence. The motions that produce the bumpiness are NOT the waves themselves, but the smaller-scale motions that RESULT FROM THEIR BREAKDOWN

Richardson number (Ri) = ratio of the work done against gravity by the vertical motions in the waves to the KE available in the shear flow

The smaller the value of Ri, the less stable the flow wrt shear instability

Most commonly accepted value for the onset of shear instability is Ri = 0.25. Once turbulence is established in a shear layer, it should be sustained so long as Ri is less than or equal to 1

In general, the larger the static stability the larger the critical shear

⚠️✈️⚠️ the relative ineffectiveness of the energy cascade mechanism in dissipating large-scale motions is due to the fact that such motions accomplish most of their transfer of E to smaller scales ONLY WITHIN CERTAIN VERY LIMITED REGIONS of the atmos

These regions = discrete patches or layers of clean air turbulence (CAT) = regions of bumpiness due to presence of vigorous small-scale motions in lowest km

⚠️⚠️ baroclinic waves form in regions of STRONG VERTICAL WIND SHEAR