In a lot of places around the world people don’t have access to some of the luxuries we take for granted: electricity, internet, running water, or even regular supplies of food and clean water. Add to that the unbearable heat of summer temperatures in places like India and half the population is out of commission for most the afternoon. But their situation is not without hope!
More than 28,000 people live in a tiny area called Daulatdia in Bangladesh. They are cramped in small huts with no running water and temperatures outside and inside can rise above 113º F.
Hot air enters the bottles from the outside and then sends cooler air out of the thinner neck. The principle is similar to the effect when you exhale into your hand with an open mouth or with pursed lips. Feel the difference for yourself!