Elevated Temperature Inversion and the Titanic's Distress Rockets
April 15, 2022
Photographer: Mila Zinkova
Summary Author: Mila Zinkova
Normally the air temperature decreases with height. However, sometimes a layer of warmer air will form above the colder air below. This is called "temperature inversion." If an inversion occurs relatively close to the ground level, and the increase in temperature from the surface to the warm layer is sufficiently steep, a superior mirage may result. Sometimes, though, the inversion will form well above the ground. Such inversions can trap smoke and other pollutants that reduce visibility. For example, on November 9, 2018, smoke from California wildfires was trapped well above the ground level as can be seen on the top photo. The Sun is hardly visible. But note that it's easier to detect, though distorted, when close to the horizon (middle photo).
The Sun on the middle photo is miraged, which indicates that there was indeed a ground-based inversion as well. Click here to see a video of this sunset. What does this have to do with the RMS Titanic's distress rockets on the night of April 15, 1912? Herbert Stone, the second officer on the SS California, testified that the rockets he observed appeared to be very low, at about the height of the ship’s masthead light. In fact, the rockets could have been exploding much higher. The presence of an elevated temperature inversion provides a plausible explanation of what Stone observed and also may explain the fact that no one on the Californian was able to hear the explosions.
After the Titanic collided with the iceberg it released steam to prevent an explosion as it sunk. It’s possible that this steam became trapped by an elevated inversion. Stone was not able to see the bursting rockets due to the inversion that trapped the steam. As with the Sun on the top photo, the Titanic’s distress rockets became more apparent as they were descending (photo of Sun on bottom photo). This is why Stone described them as low-lying rockets.
According to a reconstruction of this event by Basu, et al. (2014), the explosions of the rockets took place just below the inversion, inside the thickest quantities of the trapped smoke and condensed steam (bottom photo -- "reconstructed" image). However, Basu demonstrated that there was no surface-based inversion in proximity to the Titanic, and therefore there was no superior mirage present.