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The temperature within the Earth's crust increases about \SI{1}{\degreeCelsius} for each $\SI{30}{m}$ of depth. The thermal conductivity of the crust is $\SI{0.80}{\watt\per\kelvin\per\meter}$. \begin{abcliste} \abc Determine the heat transferred from the interior to the surface for the entire Earth in one day. \abc Compare this heat to the amount of energy incident on the Earth in one day due to radiation from the Sun. \end{abcliste}
\begin{abcliste} \abc For the transferred heat we have: \begin{align} \frac{\Delta Q}{\Delta t} &= kA\frac{\Delta T}{d}\\ &= \SI{1.36e13}{\joule\per\second} \end{align} Hence we find for the heat transferred to Earth's surface in one day: \begin{align} \Delta Q &= kA\frac{\Delta T}{d} \cdot \Delta t\\ &= \SI{1.2e18}{\joule\per\day} \end{align} \abc  \end{abcliste}
14:30, 4. July 2017  lsg a  Urs Zellweger (urs)  Current Version 
14:19, 12. June 2017  si  Urs Zellweger (urs)  Compare with Current 