Humidity
The average humidity appears to be highest around the equator. The two drops in humidity centered around -10 and 30 degrees could be explained by the climates observed along these lines of latitude. The 30 degree line of latitude passes through the Sahara Desert and the Sonoran Desert, however; the -10 degree line of latitude passes through the Amazon Rainforest. The drop in humidity along the -10 degree line of latitude could be attributed to the data being collected during the dry season in Africa. A greater examination of the cities in the data set would garner more detailed information about the relative climates represented.
Visualizations
