Beakman explains that the seasons are created by the Earth's axis being tilted. He brings Capernicus in to explain more and then uses a model to show how depending on Earth's orbit and axis the amount of sun on a given portion will affect seasons.
Phil walks us through the different layers of the atmosphere. He explains what we can expect to find at each layer and the concentration of air molecules at each level.
Bill Nye explains why it gets colder as one travels up through the atmosphere. He uses miniature replicas of a city and a mountain to support his explanation. Bill also briefly touches upon the lapse rate.