The summit of Mount Whitney, in California, is $3660 \mathrm{m}$ higher than a point in the foothills. Assume that the atmospheric lapse rate in the Mount Whitney area is the same as the global average of $-6.5^{\circ} \mathrm{C} / \mathrm{km} .$ What is the temperature of the summit of Mount Whitney when eager hikers depart from the foothill location at a temperature of $30^{\circ} \mathrm{C}$ ?