Final answer:
The greenhouse effect is the process that causes heat to accumulate in Earth's lower atmosphere, functioning similarly to window glass by trapping longer infrared rays that are re-emitted by the Earth.
Step-by-step explanation:
The mechanism responsible for causing heat to accumulate in the lower part of Earth's atmosphere is called the greenhouse effect. The atmosphere is similar to window glass in that it is transparent to incoming visible radiation and most of the Sun's infrared. These wavelengths are absorbed by the Earth and then re-emitted as infrared with much longer wavelengths due to Earth's lower temperature compared to the Sun's. Since the atmosphere traps these longer infrared rays, it keeps the Earth warmer than it would be otherwise. This effect is heightened by the presence of greenhouse gases such as carbon dioxide, which can absorb and radiate energy back to the Earth's surface, leading to an increase in Earth's surface temperature.