During the free fall of a well-fed person without a spacesuit from an altitude of 100 km above the Earth's surface, several biological-physical processes may occur:
Decompression: At this high altitude, the atmospheric pressure is extremely low, close to the vacuum of space. The sudden exposure to such low pressure can lead to rapid decompression. Without a spacesuit or proper protection, the person's body would experience a significant pressure difference, which could result in the expansion of gases within body tissues and the formation of gas bubbles. This condition is known as decompression sickness or "the bends."
Hypoxia: As the person falls from 100 km above the Earth's surface, the oxygen concentration decreases dramatically. At high altitudes, the air is thin, and the partial pressure of oxygen is significantly lower than at sea level. This reduction in oxygen availability can lead to hypoxia, which is a state of oxygen deprivation in the body. Hypoxia can cause dizziness, confusion, loss of consciousness, and potentially lead to life-threatening conditions if not addressed promptly.
Extreme cold: As the person descends through the upper atmosphere, they would be exposed to extremely cold temperatures. The temperature at an altitude of 100 km is around -70°C (-94°F). The lack of proper insulation or protective clothing would expose the person's body to the intense cold, leading to rapid heat loss, which can result in frostbite and hypothermia.
Rapid acceleration: During free fall, the person would experience rapid acceleration due to the Earth's gravitational pull. Acceleration forces can cause physiological stress on the body, including changes in blood circulation, increased heart rate, and potential discomfort or disorientation.
Atmospheric friction and heating: As the person descends through the atmosphere, the air molecules would start to exert frictional forces on their body. This friction can generate intense heat due to the high speeds involved. Without proper protection, the individual's body would be subjected to extreme heat, potentially causing burns or thermal injuries.
It's important to note that these processes would have severe consequences on the human body, and surviving such an experience without a spacesuit is highly unlikely. Free fall from an altitude of 100 km would typically require specialized equipment, training, and protective measures to ensure the safety and survival of an individual in such extreme conditions.