1. In the first couple billion years of Earth's history, the sun's luminosity (defined as power emitted per unit area of the sun surface) may have been 20% lower than it is today. This should have resulted in a surface temperature on earth which is too low for water to exist in its liquid form. a. Draw a balanced radiation budget for the Earth when the sun was 20% dimmer. Assume the related terms in this early Earth" energy budget maintain the same proportions to one another as they do today. Please label all the fluxes in the radiation budget clearly along with the revised values. b. Based on your radiation budget what is the surface temperature of the Earth under this dimmer sun? Can liquid water exist? 2. Consider an Earth that is covered mostly by land instead of water in the following proportions: 60.0% land, 30.0% water, 10.0% ice/snow. a. Calculate the planetary albedo of this "land-dominated Earth. b. Based on this value what would the net solar insolation at the Earth's surface be? Assume the other terms of the short-wave side of the radiation budget are the same as present day. Planck Radiation Curve for Incandescent Light 6.0E+06 5.0E+06 4.0E+06 Power Per Unit Area Per Unit Wavelength (W/m2/um) 3.0E+06 2.0E+06 1.0E+06 0.0E+00 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 Wavelength (um)