Credit: UCAR/NCAR

This time-lapse video shows 36 time steps in a hands-on activity that illustrates how models of Earth's atmosphere and climate work.

The What is a "model"? activity was created by the Little Shop of Physics at Colorado State University.

In the activity, students move red markers - which represent sunlight, heat, and longwave infrared radiation - between three game boards representing Earth's surface and the lower and upper parts of Earth's atmosphere. The "rules" of the model tell students how many of the red markers to move, and where, each turn. As the model runs, it illustrates how heat flows throughout the Earth system. The model illustrates how the greenhouse effect warms Earth's surface and how Earth's atmosphere is cooler at higher altitudes.

In this video, the model is started (at Time = 0) with a somewhat arbitrary set of initial conditions. At the start, the temperature (as indicated by the number of red markers) of Earth's surface (far left game board) is 19 degrees. At the start, the temperature of the lower atmosphere (middle game board) is also set at 19 degrees, while the temperature of the upper atmosphere (right board) is set at 8 degrees.

As the model runs, the three temperatures (Earth's surface, lower atmosphere, upper atmosphere) gradually adjust themselves based on the "rules" of the model.

In this model run, the Sun is left "on" all the time, so Earth's surface is in perpetual daylight. As the model "spins up", temperatures gradually rise until they reach an equilibrium state at Time = 31.

The graph below shows the changes in temperature of Earth's surface, the lower atmosphere, and the upper atmosphere over the course of this model run.

It is not realistic, of course, to have the Sun "on" all the time... as is the case in this model run. A separate video shows a model run shows the spinup of this model with alternating periods of daytime (with the Sun on) and night (with the Sun turned off). In that model run, daytime and night each last 3 turns.