There are many similarities between the sea surface temperatures and atmospheric structure during the past week and those observed during the sinking of the Titanic on April 14-15, 1912.
Should marine traffic today be worried about icebergs? The answer is revealed below!
Examining the sea surface temperatures (SSTs) today (below), you will notice cool water (around 50F) off our coast, dropping into the forties to our north. Temperatures slowly warm to our south, only hitting about 60°F in San Diego. Not very exciting or unusual.
But if you want dramatic sea surface temperature contrasts, head to the East Coast.
East of New England, ocean temperatures are in the upper 30s and 40s and are even colder near Newfoundland.
There is a huge increase in temperature south in a zone east of Maryland/Delaware. This warmth is associated with the northern extension of the Gulf Stream moving along the southeast coast.
Below is an expanded view of the above: amazing sea surface temperature changes over tens of miles.
As you can imagine, there are similarly large near-surface air temperature contrasts. To illustrate, consider the air temperature at 2 meters above the surface this morning (below). Air temperatures range from below freezing near Newfoundland to around 70°F over a few hundred miles to the south.
As we will see, there are real dangers associated with this pattern....dangers that may well have destroyed the Titanic.
Let us go back to April 14, 1912. Below is the near-surface (1000 hPa pressure) air temperature analysis for that date.
We see such superior mirages all the time here over Puget Sound, when warm air spreads over the cold water (see example below). Not how the land is elevated upwards.
So, how does this explain the inability of the crew of the Titanic to see the approaching iceberg?
And there WERE icebergs out there today! On the figure below, the blue dot shows the position of the sinking of the Titanic, the red line shows the boundary of the iceberg fields, and the numbers show how many icebergs were in each box.
Let us go back to April 14, 1912. Below is the near-surface (1000 hPa pressure) air temperature analysis for that date.
Very similar to today's pattern: very cold east of northern New England and eastern Canada, with rapid warming to the south.
How could this weather pattern have led to the demise of one of the largest passenger ships of the era, with an experienced captain and crew?
As all of you know, the Titanic was sunk by a collision with a large iceberg, which was not seen as it approached.
It appears that the iceberg was not seen because of a mirage phenomenon: a superior mirage caused by cold air near the surface and warmer air aloft.
When there is a large temperature increase with height, the atmosphere acts as a lens, causing objects to be elevated higher than they really are (see schematic below).
Courtesy: Ludovica Lorenzelli, DensityDesign Research Lab"
So, how does this explain the inability of the crew of the Titanic to see the approaching iceberg?
With cold air near the surface and warm air just to the south, one can get warm air riding over the cold air if southerly (from the south) winds develop (which happens very frequently)
Courtesy: Charles Floyd
This configuration of cold air overtopped with warm air creates a lens that creates a superior mirage in which the image of the ocean surface is elevated, obscuring the approaching iceberg, with tragic results.
Courtesy: Charles Floyd
A very similar situation happened today. Examining the vertical temperature structure today at a point near the Titanic tragedy (red dot, solid lines are sea level pressure, first figure), the dangerous situation was evident.
There is a plot of temperature with height at the point. It's there. Cold near the surface, with rapid warming just above.
But today, there is little issue with safety. Satellites give us the ability to track icebergs, and ships have highly capable radars that can spot them far ahead.
Worry about icebergs in our area? Although there are many occurrences of warm air over cold water in Northwest waters, there are no icebergs in our waters.😊
nearer my God to thee, Cliff!
ReplyDeleteThe Titanic side-swiped the iceberg. Had the ship struck the iceberg head on, it probably would have survived.
ReplyDeleteThe damage to the hull wasn't in the form of a gash as depicted in the 1997 movie. The hull was made up of thousands of overlapping riveted plates. The side-swipe collision opened up some number of hull plate boundaries along the line of contact with the berg, doing so along enough length of the hull to breach five of the ship's sixteen watertight subdivisions.
The ship might have survived with four of the sixteen subdivisions breached, but not with five. The total surface area of the myriad of plate boundary gaps was approximately twelve square feet.
That was more than enough total surface area to sink the ship when five watertight subdivisions were breached, combined with a design flaw in that the Titanic's watertight bulkheads extended only ten feet above the waterline, allowing water to flow from one flooded subdivision to another as the ship sank deeper into the water.
This kind of situation is called 'progressive flooding' and is difficult to deal with even aboard modern ships which use welded hulls as opposed to riveted plates.
And reportedly it was also determined that the rivet system used in the forward section was not of the best quality and the rivets were already highly stress loaded by the size of the ship. Thus they were somewhat ready to pop when it hit.
DeleteFascinating story about the optical illusion theory. Seems by far the most plausible reason I’ve read to date as to why they didn’t see soon enough and hit the berg to begin with, other lapses in judgement at the time not withstanding.
Tyler S, the problem with the substandard, highly stress-loaded rivets which were likely present at the ship's original construction raises another question.
DeleteIf the ship strikes the iceberg head on, rather than at a glancing side-swipe blow, how far back aft of the bow do the rivets pop loose from the plates?
Do the hull plate boundaries open up as far back as the fifth watertight subdivision, thus dooming the ship anyway even though the crumpled bow has absorbed a good portion of the energy of the collision?