Question

Do not solve the following question numerically unless specifically asked to do so. The flux from the Sun’s surface is given by L(sun)= 4πR(sun)^2 σT(sun)^4 , where T(sun) is the temperature on the Sun’s surface.

(a) What Is the incident luminosity from the Sun seen on Earth’s surface?

(b) Only a part of the luminosity incident on Earth’s surface is reflected back. The fraction of radiation reflected from Earth’s surface, or albedo, is given by A. The other part is absorbed and converted into heat, which is then emitted as thermal emission from the planet. Write an expression for the luminosity absorbed by Earth and the luminosity emitted by Earth. Assume Earth has had ample time to come up to thermal equilibrium. Use the symbol Tsurf to represent the surface temperature of Earth.

(c) Find an expression for the surface temperature of Earth, when the Earth is at thermal equilibrium. Note that thermal equilibrium means that the amount of radiation absorbed by Earth is the same as the amount of radiation emitted by Earth.

(d) Calculate the surface temperature for Earth if A=0.36. If Earth’s observed maximum temperature is 310 K, does the calculated temperature predict an accurate surface temperature? Explain.

(e) Repeat the calculation to find the surface temperature of Venus (A = 0.76). Venus has an observed maximum temperature of 750 K. Is the calculated surface temperature for Venus accurate? Why or why not?

Answer #1

Problem 2
a) What is the radiant power of the sun?
b) What is the radiant power at the surface of the earth?
c) Calculation of the solar constant
d) How much energy does the earth absorb?
e) Using the equilibrium condition to calculate the earth’s
temperature (W/O atmosphere) ? (Give a brief comment regarding your
findings)
f) Using the equilibrium condition to calculate the earth’s real
temperature (W/ atmosphere)? (Give a brief comment regarding your
findings)
Problem 3 (Very...

Consider the following simple model to describe solar
radiation incident on Earth in which the atmosphere is included. A
fraction f of the incident solar flux is absorbed by the atmosphere
and a fraction A is reflected, the rest being absorbed by the
Earth. Assume that the only heat transfer to the atmosphere from
the Earth is by radiation and that f = 0.25 and A=0.3. Find the
Temperature TE of the surface of the Earth for
radiative equilibrium. (Book...

Which of the following is closest to the distance from Earth to
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parsecs
Question 13 (1 point) Saved Which of the following is closest to
the Absolute Magnitude of a star having a luminosity of 150 times
the luminosity of the Sun ? Question 13 options: 0.0 -1.0 1.0
-2.0
Question 14 (1 point) Saved...

1/ Alpha Centauri A is a star that is remarkably like
our Sun...indeed, we can think of it as the Sun’s stellar twin.
Alpha Centauri A lies at a distence of 4.4 light-years from Earth,
and it has a luminosity of 5.88 x 10^26 W.
Calculate the apparent brightness of Alpha Centauri
A
Suppose you have a light bulb that emits 100 W of
visible light. How far away from you would you need to put that
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