 |
| Fig. 1 Sectors of Antarctica |
I. Background
In a previous post, I wrote "on to the next subject".
Today, that subject is the "impact of thermal expansion and contraction" that exists "in Antarctica".
That is a place "where the seawater in contact with tidewater glaciers is warmer than what is required to melt those glaciers".
The cause of most tidewater glacier ice melt in Antarctica is not "surface melt", the primary cause of tidewater glacier melt is the temperature of seawater deep down and all along the face of the immense fronts of tidewater glaciers.
Glaciers that reach deep down thousands of feet under the seawater down to the grounding "line" or grounding "zone" where the ice makes contact with the ground.
II. Where The Action Is
There is a lot of action there at the grounding area:
"... glaciers experienced their largest mass loss in the last 50 years, with 2023 marking the second year of widespread ice loss globally ..."
(World Meteorological Organization; cf. Widespread seawater intrusions beneath the grounded ice of Thwaites Glacier; and 2nd video below). Two of the appendices to today's post (Melt Conditions, Melt Conditions Tables) show that the seawater along the WOD zones containing tidewater glaciers in all Antarctic Sectors is cool enough to melt those tidewater glaciers all around the coastline of Antarctica.
III. TEOS-10
The TEOS-10 C++ software library was used to calculate the temperatures at which the ice would melt (the link at Fig. 1 links to additional graphs which detail those same TEOS-10 melt factors in an artistically different way).
The most critical factor in thermal expansion/contraction analysis is the "thermal expansion coefficient" (Unique thermal expansion properties of water key to the formation of sea ice on Earth).
Previously the thermal expansion factor for various oceans, including the ocean around Antarctica was considered (On Thermal Expansion & Thermal Contraction - 46).
IV. Don't Be Fooled
The notion of "thermal" change can fool us into thinking "thermal" means the warm we feel around a campfire, but that is not the case in the oceanography concepts of thermal expansion and thermal contraction.
There is no thermal expansion or contraction to any quantity of seawater (i.e. density/volume change per mass unit) unless there is a temperature change to that seawater.
The formula is: v = v0 * (1.0 + (tec * (t1 - t2))
where:
v is the volume change (thermal expansion/contraction)
v0 is the volume of the seawater being tested (must be > 0)
tec is the thermal expansion/contraction coefficient
t1 is the current temperature
t2 is the previous temperature
When t1 is equal to t2 (there was no temperature change), so tec * zero is zero; and 1.0 plus zero is 1.0; and finally v0 times 1.0 means v0 is unchanged.
A negative v means thermal contraction, a positive v0 greater than zero increases v which means thermal expansion.
Did you notice that above (in section II) I said that the seawater around Antarctica's coastline is "cool enough" to melt glaciers?
I want to re-emphasize that point, so today we take another look at thermal expansion and thermal contraction in the cool seawater around the coastline of Antarctica.
Compare the appendix Thermal Expansion with the appendix Conservative Temperature and you will see that there is thermal expansion and thermal contraction in seawater temperatures that we would freeze to death in.
There are a lot of surprising things about "thermal" dynamics:
"cold water quickly removes heat from the body which could lead to cold water shock within the first minute, loss of muscle control within 10 minutes or hypothermia within 20 to 30 minutes. When your body hits cold water, 'cold shock' can cause dramatic changes in breathing, heart rate and blood pressure."
(National Weather Service). Actually, it is the second law of thermodynamics at play in any such case, because hot/warm spontaneously flows to cool/cold.
Therefore, it is not technically correct to say that "cold water ... removes heat", but it is very correct to say it is dangerous to get into "freezing cold" water because the heat in out bodies will spontaneously flow into that cold water.
I want to shock readers into a better understanding by analyzing thermal expansion and thermal contraction in that very cold water deep under the Antarctic Ice Shelf near tidewater glacier grounding lines.
That is why I graphed thermal expansion and thermal contraction at each sector of the Antarctic coastline.
V. Thermal Expansion and Contraction In "Freezing" Seawater
The article I quoted above goes on to say:
"Fifty five degree water [12.8 °C] may not sound very cold, but it can be deadly."
(National Weather Service). The seawater temperatures that are melting tidewater glaciers all around Antarctica range from about -1 °C (30.2 °F) to about 3 °C(37.4 °F), so they are deadlier than that 55 °F (12.8 °C) water temperature which the National Weather Service said can be "deadly".
Just in case you are not shocked yet, that "killer" water temperature (55 °F) causes thermal expansion and contraction only when its temperature is changed.
In other words, 3 °C (37.4 °F ) seawater can have thermal expansion when 12.8 °C (55 deg °F) warmer water just above it can't.
VI. How Is That?
Even if it was to stay in that condition for a decade the volume would not change (no thermal expansion or thermal contraction would take place).
ONLY if there is a change in that seawater's temperature can there be any thermal expansion or thermal contraction.
It's the same with the 3 °C (37.4 °F ) seawater, no change in temperature means no change in thermal expansion or thermal contraction.
So, back to the point that if the 80 °F (26.7 °C) stays the same while the 3 °C (37.4 °F ) seawater temperature changes (warms or cools) the much colder water will have thermal expansion or thermal contraction while the much warmer water will not.
Fact: temperature change equates to thermal expansion or thermal contraction, while temperature NOT changing equates to no thermal expansion and no thermal contraction.
VII. Closing Comments
I am providing graphs that show thermal expansion/contraction, Conservative Temperature, Potential Enthalpy, and photon count (mols), in the tidewaters along the coastline of Antarctica (Appendix CT, Appendix Ho, Appendix Photons, and Appendix Thermal Expansion).
Note also that the discussions of "thermal change" are discussions of the effects of photon currents (The Photon Current, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11).
The previous post in this series is here.
