Evaporative cooling is a process by which liquids evaporate off the surface of the skin, thus cooling the body and keeping body temperatures low. In humans, the body gives off fluid to be evaporated in a process called sweating. In low humidity environments, sweating keeps humans cool, but it can also lead to dehydration and a loss of bodily salts. In humid environments, evaporative cooling is not effective for keeping the body cool because sweat will not evaporate, so overheating is a possibility. In addition, some animals do not sweat -- such as dogs -- and so they may struggle to stay cool in hot climates. To live in a warm weather climate, wear light and breathable clothing that easily allows for evaporative cooling.
Living in any warm climate requires constant attention to internal hydration levels. Drinking enough water is key to staying hydrated, and in warm climates, sweating requires continuous replenishment of fluids. Even if one is not thirsty, drinking water is essential, because warm climates can very quickly and deceptively deplete internal water reserves. Sweating may also cause a loss of salts, so simply re-hydrating with water may not always be enough, and those living in warm climates should include some salt in their diet, which can include anything from broth to sports drinks to re-hydration solution. Children and the elderly are particularly susceptible to the dangerous side effects of fluid loss in warm climates.
One way that all animals have evolved to deal with living in warm climates is to select for members that have long limbs, which help to dissipate heat from the core of the body and provide more surface area for evaporative cooling. This trend was articulated in the late 19th century by American biologist Joel Allen, and is known today as Allen's Rule. Members of species which live in hotter climates have longer arms and legs, while members closer to the poles and at cooler elevations tend to have shorter limbs. This is why many Inuit of the Arctic have short arms and are short in stature, while the Masai of equatorial Africa have extremely lanky arms and legs.
For many living in warm weather climates, exposure to the sun is mandatory. However, extended exposure to the sun in warm climates can cause cancer in the longer term, so sunscreen and lightweight long-sleeved clothing is important to consider. In the shorter term, those in warm, sunny climates must be concerned about sunburn, dehydration, and heat stroke. In particular, heat stroke can be a common problem in warm climates if one does not take the proper precautions and stay hydrated, avoid excessive sun exposure, and pay attention to internal signals from the body.
