Each of the boxes represents the number of incoming international flights to an airport. The color varies according to the ratio of international flights to domestic flights. Grey boxes have only international flight and no domestic ones. Among the others, red ones tend to have more international flights while the yellow have more domestic flights. The most bright box in the visualization is Amman airport closely followed by Zurich, Prague, Dublin etc. The visualization was filtered to show airports that have at least one international flight. The airports have been grouped by country.
The boxes represent the ratio of international to domestic flights for individual airports. Larger sizes indicate more international flights. The color represents total number of routes served by that airport. The coloring was done via two equally spaced bins highlighting the extremely busy international airports like London, Paris, Moscow and Chicago.
This is the same visualization at I2.1 with a different binning and color scheme. Red airports are the ones with most routes followed by orange, yellow, grey and black.
This is the same visualization at I2.1 with a different color scheme.