ShareEarth's Structure - What's Wrong With It?
Models are used to illustrate things that are a different size. Models can be used to illustrate something that is very small, very large, or difficult to observe. The Earth is an example of something that a model is used to help understand. Because the Earth is too large to observe, maps and globes are used as models. There are, however, problems involved with using maps or globes.Look closely at the two photographs below.
Raised relief globe
Flat surface globe
What differences seen when the two types of globes above are compared?
How is the raised relief globe a more accurate model than the flat surface globe?
Look close-up photograph of the raised relief globe below.
Why
is this globe not a good model?
Possible model problems:
Each globe is an attempt to show the placement and size of continents
in relationship to the entire Earth. When you look closely at the raised
relief globe, you see an attempt to demonstrate differences in elevation.
Mountains are shown as being raised well above the Earth's surface.
While it is true that mountains are higher than the average surface
of the Earth, the scale does not match the globe. At the scale of a
globe, the entire surface would appear flat. At this scale, when compared
with the enormous size of the entire earth, even Mt. Everest would appear
flat!
Maps
as models:
When you look at a map, you observe relationships between parts of
the Earth. Many maps are designed to allow you to place them on a wall.
These large maps are very convenient models to use when observing the
entire Earth at the same time. The major problem with maps as a model
is that it distorts objects.
Remember that the Earth is really round. When you flatten it out into a map form, it stretchs out the poles and these areas appear larger than they really are. In the flat map above, Greenland appears to be about the same size as North America. It is, however, actually much smaller!
The flat map above has elevation shown in it. You see the raised bumps indicating that their is height. The oceans have depressions that show the depths in them. Like the raised relief globe discussed earlier, these elevation areas are not to scale. Even on a large wall map, all mountains would basically appear flat compared to the entire Earth surface.
