Focus on Severe Weather: Deadly 2011 and 2013 Tornado Seasons

Understanding Weather and Climate (7th Edition) (MasteringMeteorology Series) by Edward Aguado, James E. Burt 

The World of Seven Billion

National Geographic - The World of 7 Billion

The map shows population density; the brightest points are the highest densities. Each country is colored according to its average annual gross national income per capita, using categories established by the World Bank (see key below). Some nations— like economic powerhouses China and India—have an especially wide range of incomes. But as the two most populous countries, both are lower middle class when income is averaged per capita.