Question

A group of students were instructed to create a model of the Earth to use in a global wind study. They found a lightweight metal globe with a stand that would allow the globe to rotate. The group also included a small, powerful fan in their model. After ensuring they had the globe correctly tilted to simulate the Earth's axis, one student spun the globe at a steady rate. Another student positioned the fan to blow across the globe along the equator. To determine if the model was generating observable global wind patterns, the group stopped the rotation and fan-generated wind to attach small sensors to the globe. The sensors were attached at the North Pole, 45°N latitude, the equator, 45° S latitude, and the South Pole.

The group began spinning the globe again, with one student monitoring the sensors. They collected data for 15 minutes, then compared the data to the following global wind pattern map:

image 746aede2e40e42dd8ddf5cb0f77089e5

The students noted that the patterns they observed on the globe were very different than those shown on the map. What should the students add to their model to make it a more accurate representation of global wind patterns?

A.
The students should add a heat source to simulate the heat radiated by the sun.

B.
The students should replace the metal globe with a similar plastic globe.

C.
The students should incorporate water vapor into the model to simulate the atmosphere.

D.
The students should add more sensors to the model to collect more data.

Answer 1

A.

Global wind patterns result mainly from differential heating by the Sun (warm air rising at the equator, sinking at higher latitudes) together with the Earth's rotation (Coriolis effect). The students’ model only provided rotation and a single fan flow; adding a heat source to create equator-to‑pole temperature differences will generate the convection cells (Hadley, Ferrel, polar) that drive the trade winds, westerlies and polar easterlies visible on the map.

(B is irrelevant, C alone won’t produce the large-scale pressure/temperature gradients, and D only improves measurement, not the physics.)