One atmosphere (1 atm) is the standard atmospheric pressure at sea level and is a crucial reference point in diving. It's the pressure exerted by the weight of the air above us.
Here's a breakdown of what 1 atm means in the context of diving:
- Pressure at the Surface: At sea level, the pressure exerted on a diver is 1 atm. This is the baseline from which pressure increases as you descend.
- Equivalent Pressure: 1 atm is equivalent to 14.7 pounds per square inch (psi). Imagine a column of air, one inch wide, extending from sea level to the top of the atmosphere; it would weigh 14.7 pounds.
- Depth Equivalent: While 1 atm is the pressure at the surface, for every 33 feet (approximately 10 meters) you descend in saltwater, the pressure increases by 1 atm. Therefore, at 33 feet in saltwater, a diver experiences 2 atm of pressure (1 atm from the atmosphere + 1 atm from the water).
Why is understanding atmospheres important in diving?
- Gas Laws: The behavior of gases is significantly affected by pressure. Understanding atmospheres is vital for applying gas laws (like Boyle's Law) to diving, which are essential for calculating air consumption, decompression stops, and understanding the effects of pressure on the body.
- Equipment Function: Diving equipment, such as regulators, are designed to deliver air at the ambient pressure. Understanding atmospheres ensures proper equipment function and safety.
- Physiological Effects: Pressure affects the body's absorption and release of gases. Understanding atmospheres is critical for understanding the risks of decompression sickness ("the bends") and nitrogen narcosis.
