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28-Sep-16 03:02:55
HURRICANE = A STRONG LOW PRESSURE SYSTEM
Why am I writing this article?
My reflection on low-pressure systems and hurricanes started in 1997/1998 on my way to the
Carib and back to Norway, crossing the Atlantic two times with my sail-yacht Rozinante.
In 2015/2016 I did a similar sailing with SY Rozinante II, now also visiting Cuba, the coast of
Florida up to New York and back to Europe.
During my Atlantic crossings I experienced the local squalls cloud formation and I discovered
the changing in wind direction, and I observed the coriolis effect. My understanding is that these
local low-pressures are formed in the afternoon/evening when air masses are saturated with
water vapor by solar heating and temperatures are dropping. Similar experiences happened at
anchor in the Caribbean and elsewhere. I noticed that clouds/condensation/rain /strong winds
occur mostly at night.
The drive toward understanding physical processes has been a central part of my academic
research and teaching since 1997. I have taught for 36 years, the last 27 in High School/College.
Because my profession as a professor includes mathematics, chemistry, physics and IT with
experiments for visualizations, I naturally apply the laws of science in my own research. Reading
about "Lows" and Hurricanes has of course provided the background for the information I am
presenting in this article. But my impression is that the meteorologists and the physicists are not
following this path which seems so obvious to me. In their explanation of weather systems,
meteorologists are using specialized language from the meteorology-field that is hard to
understand for normally educated people. The concept of trying to support these explanations
with some basic physics that nearly all youths meet through education is not evident. And I think
this is probably the reason why I can't find my “main point of view” (the initial event of a lowpressure system) either in the texts I have read or in conversations I have had with
meteorologists and physicists.
Thus my primary goal is to try to get my “main point of view” accepted in the world of
meteorology as well as among physicists. Such a revision would help all people – students,
professionals, and the public – to understand the basic driving forces of weather that we all –
every day, throughout our lifetimes – have ideas about.
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Basic physics in the kitchen. Equipment and Procedure:
A pair of thick gloves (make sure there are no holes in them)
A pan half-full of cold water resting on the stove (do not heat)
An empty aluminum can (beer, cola can, or similar) with approx. ¼ inch of water in it
Place the can on a burner and heat to a boil (you will hear and see this).
Allow it
to continue boiling until the whole can is filled with water-vapor.
Then, using the gloves, do this sequence quickly:
 grip the can with both hands
 place just above the pan with cold water
 turn the can rapidly upside down
 then let the can fall – in a controlled movement, guiding it with your hands – into the cold
water
Oi, oi, oi – what happened? If nothing strange happened, you must repeat!
The Physics
When water boils, it is converted to water-vapor and heat-energy is transferred to the watervapor molecules – increasing the motion of the molecules. When water-vapor is cooled, it
returns from this gas phase back into water (liquid phase) and it contracts – this is called
condensation. During vaporization, the expansion of the volume may be about 1700 times given
an equal atmospheric pressure. A corresponding contraction occurs during condensation – and
the energy is now released as heat. Just such a contraction is demonstrated by the kitchen
experiment.
The wind and the sea
Having seen the effects of extreme and rapid condensation upon an aluminum can in the kitchen,
we will move on to the heart of the matter: hurricanes, and the precise mechanism by which they
are generated.
Warm air over the ocean contains vast quantities of water-vapor (wv). Upon cooling, this watervapor condenses and creates a local area of low pressure. Surrounding air, filled with wv, is
drawn towards (the winds start to blow) the low pressure system to equalize the pressure. In this
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manner, the low pressure system is continuously fed with water vapor, which, in turn condenses
as a result of cooling – just as we have seen in the kitchen experiment. Over the ocean, a low
pressure system becomes classified as a hurricane when winds blowing towards it are strong
enough (exceeding 32.7 m/s = 117 km/h or more) for at least 10 minutes. Physicists and
meteorologists estimate that hurricanes form when ocean temperatures are above 26 ° C.
Next, the influence of the earth’s rotation causes wind to be deflected to the right, in a counterclockwise fashion (northern hemisphere). This is the Coriolis effect. See (scroll to the bottom,
under VAER(Vær), click Why wind are rotating around the low pressure and hurricanes?
Become familiar with the Coriolis effect) http://www.rozinante.net/birkebeiner/
As wv condenses, a low pressure system/hurricane will liberate heat. Air masses that are now
spinning (Coriolis effect) heat up further, the warm air rises, and are mainly brought onto the
wind systems higher up. These actions further increase the low pressure effect created by the
condensation, so that the air pressure drops even more. The action escalates.
Hurricanes towards the coast
Beneath the eye of the hurricane, the air pressure is relatively low. Wind components around the
eye will also be able to create large waves. Wind and waves moving towards the coast will lead
to further rise of sea level because of shallow waters. These three components can lead to an
extreme high tide situation. In addition, local high tide can work as a fourth component (storm
surge).
Hurricanes over land
Over land, the feeding of wv to the low pressure system gradually stops and the main driving
force, condensation, will decrease. As low pressure decreases, winds will also decrease and rain
may continue, depending on the saturation of the air. Cold air holds less water vapor than warm
air.
The birth of the hurricanes in the Atlantic
Northeast trade winds blow across the Sahara, and this heated air warms the sea so that airmasses are able to pick up a lot of wv on their way to the Caribbean/Gulf. Hurricane formation
happens spontaneously when the physical parameters are favorable. Sand fragments (or other
particles) function favorably as condensation kernels.
This process occurs most often in the geographical area between West Africa and the
Caribbean/Gulf, in the belt between approx. 5 ° and 30 ° north latitude. On the voyage passing
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over the Atlantic sea, smaller low-pressure systems, called squalls, will form. They may be
observed mostly during late afternoon through the night, as the temperature drops. Sailors must
pay attention in order to select a suitable course for the voyage considering the winds’ force and
direction, and keeping in mind action upon them of the coriolis effect. How hurricanes migrate is
primarily affected by the jet stream higher up in the atmosphere, by the prevailing trade winds,
as well as other more local lows. Several known and unknown parameters play into this. That's
why no one really has been able to predict with certainty the path a hurricane will follow. We do
know that hurricanes moving onto land generally travel to the north in the area of interest but
there are exceptions. Once they have passed the zone between the north-east Passat and the
winds blowing to the east they are influenced by westerly winds and sometimes carried to
Iceland/England/Norway.
The dynamics are evident: winds blow around a low pressure system counterclockwise (viewed
from above) and it rains heavily. But in the center, the eye of the low-pressure system, there is
remarkably less wind. Sailors travelling from North America to Europe wanting to sail fast must
calculate wind direction, strength, as well as adding/subtracting from prevailing wind
components in the area (westerly winds). If you want to sail safely and quickly, head south of the
low pressure center. Deep water sailors know this.
Squalls will occur over all waters. This is common in Kattegat, Skagerrak and the North Sea.
A few years ago, I encountered one outside Skagen/Denmark. We saw dark black clouds
building a few nautical miles away. There are no trade winds in this area. Watching the
phenomena from some distance, we did not think it was necessary to take any security actions.
But after a few minutes, strong winds – rapidly changing direction – hit the sailing yacht.
Condensation had started and followed an exponential curve, the wind was rapidly increasing,
and rain poured down. The moral is, if you see a black cloud formation at sea, be prepared and
take action.
Rolling Clouds
A good portrayal of Rolling Clouds (Roll clouds) is shown here:
http://www.youtube.com/watch?v=hKI2Atj08Xk
This phenomenon is also seen over the sea where I live. My explanation is the same as that for
hurricanes: condensation and low-pressure formation to the center of the roll. Rolling Clouds can
act in parallel in several rolling cloud formations, or "sausages," in which condensation occurs
on a leash: water vapor is pulled in two directions, and sometimes runs out of clouds. In a
hurricane, this occurs in the cloud bands, which are formed in the same manner.
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Merging of Low-pressure systems
When the distance between the two low-pressure systems is conducive, the systems will get
closer to each other and, normally, will merge.
This is called The Fujiwhara Effect, sometimes referred to as Fujiwara interaction or binary
interaction. (Named for Sakuhei Fujiwhara, the Japanese meteorologist who initially described
the effect.) This happens over all waters continuously. Binary interaction of squalls can cause the
development of a stronger “low.” If the two systems are strong storm centers, the result can be a
hurricane. The explanation is as follows: Each low-pressure system consists of a dense quantity
of air molecules in motion. The law of physics demands equalizing of different pressures within
the area, so the systems draw together.
Such a merger is often seen in northerly Atlantic waters, having arisen from remnants of
hurricanes which have moved off North America. In September 2016, remnants of hurricane
Karl threaten the Norwegian coast. In the terrifically active year 2005, former tropical storms
Maria and Nate combined to form Kristin, resulting in severe impact on Norway. Naturally this
phenomenon has piqued my interest, and caused me to wonder about the impact of the
condensation model on an even greater scale.
The Upshot
My main point is that condensation is the strongest initial driving force, the incipient event, of a
low-pressure system/hurricane to form. When water vapor contracts, volume change is about
approx. 1700 times. The warming of the air and convection (the hot air rising) is the result – not
the initial starting event – of the low pressure formation. In meteorology explanations of frontsystems/low-pressure systems the terms occlusion and occluded front are employed. This is well
described, but the physical laws working in an occluded front are not mentioned and thus not
explained. The additional terms collapsing storms and Collapsing Precipitation Cores within the
Eyewall are referred to in U.S. Landfalling Hurricanes (1994-2007).
If “collapse” refers to decrease in volume by condensation, it is accurate, and this explanation
possibly approaches my point. (However, I cannot find an explanation of the word
collapse/collapsing that is based on physical laws associated to the field meteorology anywhere.)
This vagueness is insufficient for a complete understanding of how a low-pressure system is
generated.
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Time for an audit?
In the last 16 years I have occasionally exchanged opinions with the Norwegian Meteorological
Institute (MI), http://met.no as well as meteorologists in the United States. As far as I have
understood, MI has been skeptical about my theory pinpointing condensation as the initial force.
On the other hand, US/MI has followed my idea and shown far more interest. I have visited
international hurricane pages such as those at www.noaa.gov quite frequently during this period.
My impression is that the Norwegian Meteorologists are unfortunately stuck in the early
explanations of Vilhelm Bjerknes and his era, unable and unwilling to embrace the National
Enlightenment spirit; that is – to consider renewal of explanatory models. Inquiries to
www.yr.no, Norwegian meteorological institute, have thus far yielded no response.
NOAA’s Hurricane Research Division itself, as recently as 2011, admits that “The exact
mechanism by which the eye forms remains somewhat controversial”
http://www.aoml.noaa.gov/hrd/tcfaq/A11.html And the research drawn upon here is Smith,
Shapiro, and Willoughby in the 1980s. I suggest that an audit, here in 2016, would not be out of
order in the least.
Notes
Cicero, http://www.cicero.uio.no , (CICERO the leading institute for interdisciplinary climate
research, (University of Oslo, Norway) had a good illustration of a hurricane, but my main point
was missing. The illustration is no longer present at their website. 5. Nov. 2012, I sent Cicero an
email pointing out my theory and asked for a comment. But I did not receive any reply. The 5
and 6 November 2012, I published my ideas about the initiating event of a low-pressure system
in the Oslo newspaper Dagsavisen, “New Ideas,” securing copyright to my idea.
http://www.dagsavisen.no/nyemeninger/nyemeninger-search7.802117?q=%22bj%C3%B8rn+harald+jordan%22&sortby (Norwegian)
Also see: www.rozinante.net/birkebeiner (Norwegian and earlier English version)
Scroll down to section Vær = Weather
The “Illustration of a hurricane” attached to this article was created by
http://www.nyhetsgrafikk.no with my corrections.
© Bjørn Harald Jordan, 29 Sept. 2016.