Final answer:
The majority of energy causing the 6ºC temperature in the winter at Ferris is from the Sun, with the greenhouse effect contributing to heat retention.
Step-by-step explanation:
The source of most of the energy that causes the temperature of Ferris to be 6ºC (43ºF) in the winter is the Sun. The Sun delivers energy to the Earth's atmosphere at a continuous rate, a portion of which is absorbed and re-radiated as heat. However, only about 70.7% of the solar energy makes it to the Earth's surface due to reflection by clouds and other surfaces. Moreover, the greenhouse effect, primarily due to carbon dioxide (CO2) and methane emissions, traps some of this re-radiated energy in the atmosphere, which contributes to warming and maintaining the temperature higher than it otherwise would be. The balance between the solar energy received and the infrared radiation emitted by the Earth is what determines the average temperature experienced in any region, including its seasonal variation.