How might Venus' atmosphere have evolved to its present state through a runaway greenhouse effect?

Explained

Explanation:

Venus is the second and the Hottest planet of the solar system. Venus' atmosphere is very thick that contain considerable amount of CO_2 and H2O.

Both CO2 and H2O are green house gases. They have the ability to absorb heat and does not it reflect back into the atmosphere. Due continuous green house effect the temperature of the Venus kept rising, making it the hottest planet of the solar system. It is estimated by the researchers that the Venus must have had water in the past, owing to suns heat the water evaporated into the Atmosphere, water vapor being a green house gas cause the heating of the planet.