Convection is heat transfer from flow of a fluid or gas over an object. Examples of convective heat transfer might be standing in front of a fan or placing one's hand into a flowing stream of water. In reality, evaporation is a combination of conduction and convection, but it is often considered a unique mechanism because it is so important in human heat dissipation. Sweating is the mechanism humans use to take advantage of evaporation heat loss. Hyperthermia is a condition where the body temperature is above normal.
Heat stroke is a temperature-related illness that overwhelms the body's ability to dissipate heat.
It often begins with dehydration and electrolyte imbalances and can progress to multi-organ failure and death. It can develop over the course of days in the dehydrated elderly or over the course of hours in the young, athletic patient. Patients often have a temperature over 105 F and mental status compromise. They may be tachycardic, tachypneic, and hypotensive. In many cases, the patient is hot and dry, because the sweating mechanism is not operative.