Astronomy 207 Midterm 4 - UofC Exam Actual Questions and Answers Verified 100% Correct 2026.

Astronomy 207 Midterm 4 - UofC Exam Actual Questions and Answers Verified 100% Correct 2026. Earth's stratosphere is heated primarily by which process? A) Convection from the Earth's surface. B) Absorption of infrared radiation by greenhouse gases. C) Absorption of visible light by ozone. D) Absorption of ultraviolet radiation by ozone. E) Atoms and molecules absorb infrared sunlight. - ANSWER -D) Absorption of ultraviolet radiation by ozone. Convection occurs in the troposphere but not in the stratosphere because A) the troposphere is warmer than the stratosphere. B) the troposphere is cooler than the stratosphere. C) lower altitudes of the troposphere are warmer than higher altitudes, unlike in the stratosphere. D) higher altitudes of the troposphere are warmer than lower altitudes, unlike in the stratosphere. E) the troposphere contains fewer greenhouse gases than the stratosphere. - ANSWER -E) the troposphere contains fewer greenhouse gases than the stratosphere. Why are sunsets and sunrises red? a) The Sun emits more red light when it's near the horizon. b) Sunlight must pass through more atmosphere to reach our eyes at those times, which means it passes through a larger volume of red air molecules. c) The lower temperatures of morning and evening (compared to midday) make the sky redder in color. d) Sunlight must pass through more atmosphere to reach our eyes at those times, so more blue light is scattered away. - ANSWER -d) Sunlight must pass through more atmosphere to reach our eyes at those times, so more blue light is scattered away. Why does convection occur in the troposphere, but not in the stratosphere? a) The troposphere is warmer than the stratosphere. b) The troposphere is cooler than the stratosphere. c) Density decreases with altitude in the troposphere, but this trend reverses in the stratosphere. d) The troposphere contains a smaller proportion of greenhouse gases than the stratosphere. e) Temperature decreases with altitude in the troposphere, but this trend reverses in the stratosphere. - ANSWER -e) Temperature decreases with altitude in the troposphere, but this trend reverses in the stratosphere. Earth has gone in and out of numerous ice ages over the past couple million years. Which of the following was generally true during all those ice ages? a) The atmospheric carbon dioxide concentration was much higher than it is today. b) The continents were closer together than they are today. c) The continents were farther apart than they are today. d) There were much larger mammals than there are today. e) The atmospheric carbon dioxide concentration was much lower than it is today. - ANSWER -e) The atmospheric carbon dioxide concentration was much lower than it is today. Geological evidence points to a history of extended ice ages in Earth's history. How did Earth recover from this snowball phase? A) The increased ice coverage on Earth's surface absorbed more sunlight than water and rocks, thus gradually heating Earth until the ice melted. B) Life vanished, leading to an increase in CO2, and increased global warming, eventually melting the ice. C) Volcanoes continued to inject CO2 into Earth's atmosphere, increasing the greenhouse effect to the point where ice melted. D) Plate tectonics gradually subducted all the ice below Earth's surface. E) As the Sun aged, it grew brighter and increased Earth's temperature, melting the ice. - ANSWER -C) Volcanoes continued to inject CO2 into Earth's atmosphere, increasing the greenhouse effect to the point where ice melted. Where did the molecular oxygen in Earth's atmosphere come from? Question 39 options: a) photosynthesis by living organisms b) outgassing from volcanoes c) evaporation from the oceans d) chemical reactions with surface rocks e) the breakdown of water molecules by sunlight - ANSWER -a) photosynthesis by living organisms Why do jovian planets bulge around the equator, that is, have a "squashed" appearance? A) They are much more massive than the terrestrial planets. B) Their large systems of moons and rings gravitationally attract the mass around the equator more. C) Their rapid rotation flings the mass near the equator outward. D) Their internal heat sources exert a pressure against the sides of the planets. E) all of the above - ANSWER -C) Their rapid rotation flings the mass near the equator outward. Which jovian planets have compositions dominated by hydrogen compounds such as methane, ammonia, and water? a) Saturn and Uranus b) Jupiter and Neptune c) Saturn, Uranus, and Neptune d) Saturn and Neptune e) Uranus and Neptune - ANSWER -e) Uranus and Neptune Why is Jupiter denser than Saturn? A) It is made of a different composition than Saturn, including a higher proportion of hydrogen compounds and rocks. B) The extra mass of Jupiter compresses its interior to a greater extent than that of Saturn. C) Its core is much larger than Saturn's. D) It has a greater proportion of helium to hydrogen compared to Saturn.