The hottest air temperature ever recorded on Earth is 56.7°C (134°F) in Death Valley, California, and the highest ground temperature, 80.8°C (177.4°F), was recorded in the Lut Desert of Iran. Scientists define a desert not by heat but by dryness, less than about 250 millimetres of rain a year. Many deserts lie near 30° latitude, where air rising at the equator, having lost its moisture, sinks and warms, which stops cloud formation. Clear skies let strong sunlight heat dry ground that has little moisture to cool it, but the same dry air lets heat escape at night, so deserts can be very cold after dark.

Hampi is a UNESCO World Heritage Site in Karnataka, India, with more than 1,600 surviving remains spread over 4,100 hectares. It was the capital of the Vijayanagara Empire from 1336 to 1565. Travellers from Persia and Portugal described it as a prosperous, wealthy and grand city with temples, markets and farms along the Tungabhadra River. By 1500 it was estimated to be the world's second-largest city after Beijing, and probably India's richest at the time. In 1565 a coalition of Muslim sultanates defeated the Vijayanagara Empire, its capital was conquered and destroyed, and the city was left in ruins. Hampi remains a religious centre, with the active Virupaksha Temple at its heart.