Balance radiactivo S(1-a)/4 = T e 4 S radiacion solar, a=albedo constante de Stefan-Boltzmann Te = temperatura de emision efectiva. Superficie T ~ 290K, T e ~ 255K. T e = T- Z e Implica emision desde ~5km.
Fig 1. Held and Soden (2000)
Retroalimentacion de vapor de agua aumenta la respuesta al forzante. Sin retroalim vapor de agua: Q=5.35Ln(CO2/CO2 0 ) / (logCO2x2)= o ~ 1°C Con retroalim vapor de agua: T logCO2x2) = o ·(1- H20 ) -1 H20 provee una medida de la retroalimentacion del vapor de agua. Modelos indican ~0.4 para RH=cte. O sea : T logCO2x2) ~ 1.7°C Si H20 >= 1 la retroalimentacion no tiene fin (runaway).
Fig 2, Held and Soden (2000) Efecto invernadero Vapor de agua TSM Mayor retroalim de vapor de agua: <- donde hay mas vapor de agua <- donde TSM es mayor
Retroalimentacion de vapor de agua
Modelos representan la distribucion de humedad relativa observada con ciertos errores
Cada vez se entiende menos: From IPCC Reports: 1990: The best understood feedback mechanism is water vapor feedback, and this is intuitively easy to understand (63). 1992: There is no compelling evidence that water vapor feedback is anything other than positivealthough there may be difficulties with upper tropospheric water vapor (64). 1995: Feedback from the redistribution of water vapor remains a substantial source of uncertainty in climate modelsMuch of the current debate has been addressing feedback from the tropical upper troposphere (65).
Third Assessment Report
IPCC 2007 lation (Fig. 13). Confidence in GCMs water vapor feedbacks depends on how much the (parameterized) details of cloud and convective microphysics are critical for simulating the relative humidity distribution and its change under global warming. This issue remains some- what uncertain. Unidimensional modeling studies have emphasized the sensitivity of the simulated relative hu- midity distribution to microphysical parameters (Rennó et al. 1994), and it has been suggested that this Bony et al (2006)
Snowball Earth Supuestamente ocurrio hace: 2220 Ma 710 Ma 640 Ma