Lab 5

This week we were instructed to make two world maps in three different types of projections: conformal, equal area, and equidistant. I chose to make mine on the following projections:

Conformal:
Mercator Conformal
Gall Stereographic Conformal

Equal Area:
Mollweide Equal Area
Behrmann Equal Area

Equidistant:
Conic Equidistant
Sinusoidal Equidistant

The following are the projections along with the distance of each from Washington D.C. to Kabul, Afghanistan, and around the Equator.

Mercator Conformal:
   Distance from Washington D.C. to Kabul, Afghaninstan:  10,105Mi
   Distace at the Equator:  24,957Mi
Gall Stereographic Conformal:
  Distance from Washington D.C. to Kabul, Afghaninstan: 7,168Mi
  Distace at the Equator: 17,168Mi

Mollweide Equal Area:
Distance from Washington D.C. to Kabul, Afghaninstan: 7,924Mi
Distace at the Equator: 22,437Mi
Behrmann Equal Area:
Distance from Washington D.C. to Kabul, Afghaninstan: 8,786Mi
Distace at the Equator: 21,632Mi

Conic Equidistant:
Distance from Washington D.C. to Kabul, Afghaninstan: 6,985Mi
Distace at the Equator: 25,329Mi
Sinusoidal Equidistant:
Distance from Washington D.C. to Kabul, Afghaninstan: 8,168Mi
Distace at the Equator: 24,884Mi

Map projections just by their nature will always have distortions and inaccuracies in them. What we try to do when we use maps is to try to pick a map projection that fits our purpose. For example, if we needed a bearing while on a ship at sea, we would need a map projection that retains angles well.  Conformal map projections do this well.  We can see that in conformal projections all the angles are 90 degrees, as in the maps that I posted. Unfortunately the area closest to the poles have lots of distortions that make these projections less and less useful as you move away from the standard parallel.

If our goal was to preserve area, then the equal area maps are what we would be working with. Some of these maps work well, but the angles are not preserved well as in the Mollweide Equal Area projection.  It is clear that in this map, the only 90 degree angles exist where the Prime Meridian and the Equator cross.  Although the Behrmann Equal Area Projection preserves the angles, the continents are greatly distorted and thinned out.  The only use for this map is to show the different areas.

The last projection that we worked with and the one that I think we should have been working with since the beginning is the equidistant projections. These projections focus on preserving the distance from one point to another. These projections, unfortunately, also have to be used accordingly. Since the Sinusoidal Equidistant projection is focused on the Equator, it preserves the distances from the equator. Since neither Washington D.C., nor Kabul is at the center of this map projection, the distance is not preserved. The distance that it showed from Washington D.C. to Kabul, Afghanistan was 8,168, which is 1,246 Miles off of the actual 6,922 Miles. The Conic Equidistant Projection turns out to be the closest at only 63 Miles off. This projection is closer to the actual distance because the two cities are closer to the standard parallel of the projection.

As we can see, knowing how to use map projections is just as important as being able to choose which one to use. If we would have chosen a map projection that was focused at either Washington D.C. or Kabul, our measurements would have been more accurate. Lastly, I think that some prior knowledge of the actual distance would great because without this knowledge, we could have picked the sinusoidal map projection and not have known that we were very inaccurate.