MasteringAstronomy Assignment #4
Visual Activity: Exploring the Cause of the Greenhouse Effect
On a cloudless day, what happens to most of the visible light headed toward Earth?
It reaches Earth’s surface, where some is reflected and some is absorbed.
On a day with complete cloud cover, what happens to the visible light headed toward Earth?
The clouds reflect much of it back to space, though some still reaches the surface
What happens to the energy that the ground absorbs in the form of visible sunlight?
It is returned upward in the form of infrared light.
The greenhouse effect raises Earth’s surface temperature (from what it would be otherwise) because
the infrared light radiated by Earth’s surface __________.
is temporarily absorbed by greenhouse gases and then reemitted in random directions
Internal Structure of Earth
Part A
We currently believe that Earth’s structure is made up of six main regions. Three of these regions can
be directly observed and three cannot. Label the six major regions of Earth in the following image.
Part B
Although scientists cannot directly observe Earth’s mantle or core, they can learn about these regions
indirectly by observing the behavior of seismic waves from earthquakes. Seismic waves come in two
basic forms (see figure). Pressure (P) waves move material back-and-forth in the direction of the
waves' motion. Compressing and expanding a slinky will produce this sort of oscillation. Shear (S)
waves, on the other hand, move material side-to-side in directions perpendicular to the waves' motion.
The oscillations of a jump rope, a guitar string, and the ocean surface are all examples of shear
waves.
