What is the equation for calculating PSGI?

The equation for calculating PSGI, or Pressure Speed Gradient Index, is based on the relationship between the driving depth and gas pressure. The formula D x 0.445 relates the depth in meters (D) to the corresponding pressure in bar, where 0.445 is a conversion factor that translates the depth of water into pressure.

In diving physics, this equation is particularly valuable because it allows divers and dive planners to assess how pressure affects gas density, which is critical for avoiding decompression sickness and understanding how gases behave under varying conditions of pressure. Knowing the PSGI helps divers understand the implications of depth on their breathing gas mixture and make informed decisions about their dive plans.

Other options do not reflect established equations in dive physics relevant to PSGI, making this choice the only correct one.