Final answer:
Venus experiences a runaway greenhouse effect due to its thick atmosphere of carbon dioxide and sulfuric acid clouds, resulting in a high surface temperature as heat is trapped, creating a cycle of continuous warming.
Step-by-step explanation:
Venus' close proximity to the sun and its high levels of carbon dioxide create what is known as the runaway greenhouse effect. The atmosphere of Venus is composed of approximately 96% carbon dioxide, which is substantially higher than Earth's.
This composition, along with thick clouds containing sulfuric acid, prohibits the efficient escape of infrared radiation, or heat, from the planet's surface back into space. As a result, the planet experiences an extreme version of the greenhouse effect, causing its surface temperature to rise to an average of around 450°C (842°F).
The high surface temperature on Venus is maintained because the planet has to radiate as much energy as it receives from the Sun, but this only occurs when the lower atmosphere is at this elevated temperature, leading to a self-perpetuating cycle of warming.