EPOD - a service of USRA
The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.
Elevated Temperature Inversion and the Titanic's Distress Rockets
April 15, 2022
Sunset 11-9-2018
Rockets
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.
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More...
Atmospheric Effects Links
* Atmospheric Optics
* Optic Picture of Day: Gruppo Astrofili Galileo Galilei
* Color and Light in Nature
* The Colors of Twillight and Sunset
* Refraction Index
* Image Gallery: Atmospheric Effects
* What is a Rainbow?
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Space Research Association.
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