Map 2 critique

This map displays the annual direct (perpendicular to the land area) solar radiation received by a particular area in the United States.  This map makes great use of its color scheme, getting darker as you approach areas with higher levels of radiation and lighter as you approach areas of less direct solar radiation. This map is well balanced, and is very clear and legible.  The only aspect missing is a scale, but may not be necessary due to the data being map.  Visual hierarchy is also adequate and emphasis is placed on data.

Source: http://www.nrel.gov/gis/solar.html