Approximately 23% of the energy available at the Earth's surface is used for evaporating water (either evaporation from free water surfaces or transpiration from plants). How much water, in km' year", is evaporated? Assume the energy available at the surface of the Earth is 553 W m**, the latent heat of
vaporization is 2.5 x $10^{6}$ J $kg^{-1}$, the density of water is $1. 0 \times1 0^{1 2} \, \mathrm{k g} \ \mathrm{k m}^{-3}$ , the radius of Earth is
6.38 x $1 0^{6}$ m, and there are 31,536,000 seconds in a year.

Options:
A. $$
\mathrm{E v a p ~ E n e r g y}=0. 2 8 \ast5 5 3 \mathrm{~ W ~ m^{-2}= 1 5 5 ~ W ~ m^{-2} ~}
$$
$$
1 \mathrm{W} \mathrm{m}^{-2}=1 \mathrm{J s}^{-1} \mathrm{m}^{-2}
$$
$$
\mathrm{S A ~ E a r t h}=4 * \pi* ( 6. 3 8 \times1 0^{6} )^{2}=5. 1 \times1 0^{1 4} \mathrm{~ m}^{2}
$$
$$
( 1 5 5 \mathrm{J s}^{-1} \mathrm{m}^{-2} \ast3 1, 5 3 6, 0 0 0 \mathrm{s y e a r}^{-1} \ast5. 1 \times1 0^{1 4} \mathrm{m}^{2} ) / 2. 5 \times1 0^{6} \mathrm{J k g}^{-1}=1. 0 1 \mathrm{~ x ~} 1 0^{1 8} \mathrm{~ k g}
$$
$$
1. 0 1 \times1 0^{1 8} \operatorname{k g} / 1. 0 \times1 0^{1 2} \operatorname{k g} \operatorname{k m}^{-3}=1. 0 1 \times1 0^{6} \operatorname{k m}^{3}
$$
B. $$
\mathrm{E v a p ~ E n e r g y}=0. 2 5 \ast5 5 3 \mathrm{~ W ~ m^{-2}= 1 3 8 ~ W ~ m^{-2} ~}
$$
$$
1 \mathrm{W} \mathrm{m}^{-2}=1 \mathrm{J s}^{-1} \mathrm{m}^{-2}
$$
$$
\mathrm{S A ~ E a r t h}=4 * \pi* ( 6. 3 8 \times1 0^{6} )^{2}=5. 1 \times1 0^{1 4} \mathrm{~ m}^{2}
$$
$$
( 1 3 8 \mathrm{J s}^{-1} \mathrm{m}^{-2} \ast3 1, 5 3 6, 0 0 0 \mathrm{s y e a r}^{-1} \ast5. 1 \times1 0^{1 4} \mathrm{m}^{2} ) / 2. 5 \times1 0^{6} \mathrm{J k g}^{-1}= 8. 9 6 \mathrm{~ x ~} 1 0^{1 7} \mathrm{~ k g}
$$
$$
8. 9 6 \times1 0^{1 7} \operatorname{k g} / 1. 0 \times1 0^{1 2} \operatorname{k g} \operatorname{k m}^{-3}=8. 9 6 \times1 0^{5} \operatorname{k m}^{3}
$$
C. $$
\mathrm{E v a p ~ E n e r g y}=0. 2 3 \ast5 5 3 \mathrm{~ W ~ m^{-2}=1 2 7 ~ W ~ m^{-2} ~}
$$
$$
1 \mathrm{W} \mathrm{m}^{-2}=1 \mathrm{J s}^{-1} \mathrm{m}^{-2}
$$
$$
\mathrm{S A ~ E a r t h}=4 * \pi* ( 6. 3 8 \times1 0^{6} )^{2}=5. 1 \times1 0^{1 4} \mathrm{~ m}^{2}
$$
$$
( 1 2 7 \mathrm{J s}^{-1} \mathrm{m}^{-2} \ast3 1, 5 3 6, 0 0 0 \mathrm{s y e a r}^{-1} \ast5. 1 \times1 0^{1 4} \mathrm{m}^{2} ) / 2. 5 \times1 0^{6} \mathrm{J k g}^{-1}= 8. 1 9 \mathrm{~ x ~} 1 0^{1 7} \mathrm{~ k g}
$$
$$
8. 1 9 \times1 0^{1 7} \operatorname{k g} / 1. 0 \times1 0^{1 2} \operatorname{k g} \operatorname{k m}^{-3}=8. 1 9 \times1 0^{5} \operatorname{k m}^{3}
$$
D. $$
\mathrm{E v a p ~ E n e r g y}=0. 2 6 \ast5 5 3 \mathrm{~ W ~ m^{-2}= 1 4 4 ~ W ~ m^{-2} ~}
$$
$$
1 \mathrm{W} \mathrm{m}^{-2}=1 \mathrm{J s}^{-1} \mathrm{m}^{-2}
$$
$$
\mathrm{S A ~ E a r t h}=4 * \pi* ( 6. 3 8 \times1 0^{6} )^{2}=5. 1 \times1 0^{1 4} \mathrm{~ m}^{2}
$$
$$
( 1 4 4 \mathrm{J s}^{-1} \mathrm{m}^{-2} \ast3 1, 5 3 6, 0 0 0 \mathrm{s y e a r}^{-1} \ast5. 1 \times1 0^{1 4} \mathrm{m}^{2} ) / 2. 5 \times1 0^{6} \mathrm{J k g}^{-1}= 9. 2 1 \mathrm{~ x ~} 1 0^{1 7} \mathrm{~ k g}
$$
$$
9. 2 1 \times1 0^{1 7} \operatorname{k g} / 1. 0 \times1 0^{1 2} \operatorname{k g} \operatorname{k m}^{-3}=9. 2 1 \times1 0^{5} \operatorname{k m}^{3}
$$
E. $$
\mathrm{E v a p ~ E n e r g y}=0. 1 9 \ast5 5 3 \mathrm{~ W ~ m^{-2}= 1 0 5 ~ W ~ m^{-2} ~}
$$
$$
1 \mathrm{W} \mathrm{m}^{-2}=1 \mathrm{J s}^{-1} \mathrm{m}^{-2}
$$
$$
\mathrm{S A ~ E a r t h}=4 * \pi* ( 6. 3 8 \times1 0^{6} )^{2}=5. 1 \times1 0^{1 4} \mathrm{~ m}^{2}
$$
$$
( 1 0 5 \mathrm{J s}^{-1} \mathrm{m}^{-2} \ast3 1, 5 3 6, 0 0 0 \mathrm{s y e a r}^{-1} \ast5. 1 \times1 0^{1 4} \mathrm{m}^{2} ) / 2. 5 \times1 0^{6} \mathrm{J k g}^{-1}= 6. 7 3 \mathrm{~ x ~} 1 0^{1 7} \mathrm{~ k g}
$$
$$
6. 7 3 \times1 0^{1 7} \operatorname{k g} / 1. 0 \times1 0^{1 2} \operatorname{k g} \operatorname{k m}^{-3}=6. 7 3 \times1 0^{5} \operatorname{k m}^{3}
$$
F. $$
\mathrm{E v a p ~ E n e r g y}=0. 2 0 \ast5 5 3 \mathrm{~ W ~ m^{-2}= 1 1 0 ~ W ~ m^{-2} ~}
$$
$$
1 \mathrm{W} \mathrm{m}^{-2}=1 \mathrm{J s}^{-1} \mathrm{m}^{-2}
$$
$$
\mathrm{S A ~ E a r t h}=4 * \pi* ( 6. 3 8 \times1 0^{6} )^{2}=5. 1 \times1 0^{1 4} \mathrm{~ m}^{2}
$$
$$
( 1 1 0 \mathrm{J s}^{-1} \mathrm{m}^{-2} \ast3 1, 5 3 6, 0 0 0 \mathrm{s y e a r}^{-1} \ast5. 1 \times1 0^{1 4} \mathrm{m}^{2} ) / 2. 5 \times1 0^{6} \mathrm{J k g}^{-1}= 7. 1 3 \mathrm{~ x ~} 1 0^{1 7} \mathrm{~ k g}
$$
$$
7. 1 3 \times1 0^{1 7} \operatorname{k g} / 1. 0 \times1 0^{1 2} \operatorname{k g} \operatorname{k m}^{-3}=7. 1 3 \times1 0^{5} \operatorname{k m}^{3}
$$
G. $$
\mathrm{E v a p ~ E n e r g y}=0. 2 1 \ast5 5 3 \mathrm{~ W ~ m^{-2}= 1 1 6 ~ W ~ m^{-2} ~}
$$
$$
1 \mathrm{W} \mathrm{m}^{-2}=1 \mathrm{J s}^{-1} \mathrm{m}^{-2}
$$
$$
\mathrm{S A ~ E a r t h}=4 * \pi* ( 6. 3 8 \times1 0^{6} )^{2}=5. 1 \times1 0^{1 4} \mathrm{~ m}^{2}
$$
$$
( 1 1 6 \mathrm{J s}^{-1} \mathrm{m}^{-2} \ast3 1, 5 3 6, 0 0 0 \mathrm{s y e a r}^{-1} \ast5. 1 \times1 0^{1 4} \mathrm{m}^{2} ) / 2. 5 \times1 0^{6} \mathrm{J k g}^{-1}= 7. 4 3 \mathrm{~ x ~} 1 0^{1 7} \mathrm{~ k g}
$$
$$
7. 4 3 \times1 0^{1 7} \operatorname{k g} / 1. 0 \times1 0^{1 2} \operatorname{k g} \operatorname{k m}^{-3}=7. 4 3 \times1 0^{5} \operatorname{k m}^{3}
$$
H. $$
\mathrm{E v a p ~ E n e r g y}=0. 2 2 \ast5 5 3 \mathrm{~ W ~ m^{-2}= 1 2 2 ~ W ~ m^{-2} ~}
$$
$$
1 \mathrm{W} \mathrm{m}^{-2}=1 \mathrm{J s}^{-1} \mathrm{m}^{-2}
$$
$$
\mathrm{S A ~ E a r t h}=4 * \pi* ( 6. 3 8 \times1 0^{6} )^{2}=5. 1 \times1 0^{1 4} \mathrm{~ m}^{2}
$$
$$
( 1 2 2 \mathrm{J s}^{-1} \mathrm{m}^{-2} \ast3 1, 5 3 6, 0 0 0 \mathrm{s y e a r}^{-1} \ast5. 1 \times1 0^{1 4} \mathrm{m}^{2} ) / 2. 5 \times1 0^{6} \mathrm{J k g}^{-1}= 7. 8 6 \mathrm{~ x ~} 1 0^{1 7} \mathrm{~ k g}
$$
$$
7. 8 6 \times1 0^{1 7} \operatorname{k g} / 1. 0 \times1 0^{1 2} \operatorname{k g} \operatorname{k m}^{-3}=7. 8 6 \times1 0^{5} \operatorname{k m}^{3}
$$
I. $$
\mathrm{E v a p ~ E n e r g y}=0. 2 4 \ast5 5 3 \mathrm{~ W ~ m^{-2}= 1 3 3 ~ W ~ m^{-2} ~}
$$
$$
1 \mathrm{W} \mathrm{m}^{-2}=1 \mathrm{J s}^{-1} \mathrm{m}^{-2}
$$
$$
\mathrm{S A ~ E a r t h}=4 * \pi* ( 6. 3 8 \times1 0^{6} )^{2}=5. 1 \times1 0^{1 4} \mathrm{~ m}^{2}
$$
$$
( 1 3 3 \mathrm{J s}^{-1} \mathrm{m}^{-2} \ast3 1, 5 3 6, 0 0 0 \mathrm{s y e a r}^{-1} \ast5. 1 \times1 0^{1 4} \mathrm{m}^{2} ) / 2. 5 \times1 0^{6} \mathrm{J k g}^{-1}= 8. 5 2 \mathrm{~ x ~} 1 0^{1 7} \mathrm{~ k g}
$$
$$
8. 5 2 \times1 0^{1 7} \operatorname{k g} / 1. 0 \times1 0^{1 2} \operatorname{k g} \operatorname{k m}^{-3}=8. 5 2 \times1 0^{5} \operatorname{k m}^{3}
$$
J. $$
\mathrm{E v a p ~ E n e r g y}=0. 1 8 \ast5 5 3 \mathrm{~ W ~ m^{-2}= 9 9 . 5 ~ W ~ m^{-2} ~}
$$
$$
1 \mathrm{W} \mathrm{m}^{-2}=1 \mathrm{J s}^{-1} \mathrm{m}^{-2}
$$
$$
\mathrm{S A ~ E a r t h}=4 * \pi* ( 6. 3 8 \times1 0^{6} )^{2}=5. 1 \times1 0^{1 4} \mathrm{~ m}^{2}
$$
$$
( 9 9 . 5 \mathrm{J s}^{-1} \mathrm{m}^{-2} \ast3 1, 5 3 6, 0 0 0 \mathrm{s y e a r}^{-1} \ast5. 1 \times1 0^{1 4} \mathrm{m}^{2} ) / 2. 5 \times1 0^{6} \mathrm{J k g}^{-1}= 6. 4 0 \mathrm{~ x ~} 1 0^{1 7} \mathrm{~ k g}
$$
$$
6. 4 0 \times1 0^{1 7} \operatorname{k g} / 1. 0 \times1 0^{1 2} \operatorname{k g} \operatorname{k m}^{-3}=6. 4 0 \times1 0^{5} \operatorname{k m}^{3}
$$
Answer: C