# Planet Emission Temperature Climate Model

Use the interactive simple climate model on this page to answer the following questions. If you do not understand the terms used in the question, you might need to go to the alcove entrance or review previous material. Instructions on using the model are given below.

QUESTIONS

• As you increase the solar energy output (the solar constant), what happens to the effective temperature of the planet?
• Why does the effective temperature of the planet change with a change in energy output of the sun?
• Explain why changing your planet's albedo modifies the planet's effective temperature.
• When is it useful to use a log scale?
• When is it useful to use a linear scale?
• Earth's average planetary emission temperature is approximately 255K. What is the range of possible albedos and energy output of the sun that satisfy Earth's current emission temperature?
• Why does Venus have a lower emission temperature than Earth? (Use your planet to validate your hypothesis)

When you are finished, you can experiment with another simplified climate model, one that has an atmosphere.

Instructions:

You control two properties of a planet: albedo and its distance from the Sun. The albedo is the ratio of the energy (radiation) reflected by an object to the energy incident upon it. You also control the energy output of the sun. As you vary these parameters the emission temperature of the planet changes and is plotted on a graph as a function of distance from the Sun. The temperature axis can be plotted as degrees Kelvin (K), Celsius (C), or Fahrenheit (F). The emission temperature of the nine planets is plotted with the following key: Mercury (M), Venus (V), Earth (E) Mars (M), Jupiter (J), Saturn (S), Uranus (U), Neptune (N) and Pluto (P). Both axes can be plotted on a linear or logarithmic scale, you decide.

The mathematics of the model are also available.

The Verner E. Suomi Virtual Museum development funded in part by the National Science Foundation Grant #EAR9809458.  Material presented is Copyrighted (C) 1999 by Steve Ackerman and Tom Whittaker.  If you have questions or comments, please let us know!