Atmosphere of Venus
In 1761, Russian polymath Mikhail Lomonosov observed an arc of light surrounding the part of Venus off the Sun's disc at the beginning of the egress phase of the transit and concluded that Venus has an atmosphere. In 1940, Rupert Wildt calculated that the amount of CO in the Venusian atmosphere would raise surface temperature above the boiling point for water. This was confirmed when Mariner 2 made radiometer measurements of the temperature in 1962. In 1967, Venera 4 confirmed that the atmosphere consisted primarily of carbon dioxide.
TRAPPIST-1b
The refined density of TRAPPIST-1b, along with the planet's transmission spectrum, indicate that its atmosphere is made mainly of vaporized water. The atmosphere has likely risen the planet's surface temperature to about 750-1500 K, which would require an atmospheric pressure between 10 (10) to 10 (10,000) bar, potentially thicker than Venus's atmosphere. TRAPPIST-1b's atmosphere is likely very similar to that of Venus.