APOD: Cyclone Paths on Planet Earth (2021 Sep 15)

[APOD Robot]

Cyclone Paths on Planet Earth

Explanation: Where on Earth do cyclones go? Known as hurricanes when in the Atlantic Ocean and typhoons when in the Pacific, the featured map shows the path of all major storms from 1985 through 2005. The map shows graphically that cyclones usually occur over water, which makes sense since evaporating warm water gives them energy. The map also shows that cyclones never cross -- and rarely approach -- the Earth's equator, since the Coriolis effect goes to zero there, and cyclones need the Coriolis force to circulate. The Coriolis force also causes cyclone paths to arc away from the equator. Although long-term trends remain a topic of research, evidence indicates that hurricanes have become, on the average, more powerful in the North Atlantic over the past 30 years, and their power is projected to keep increasing.

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[RocketRon]

Fascinating.

And South America doesn't get them - except for a solitary example ??
Are there any theories about why that may be ?

[Alex_515]

Oddly enough, for the Pacific typhoons located in the Northern Hemisphere, it looks like there are two distinct regions on the right and left and a kind of hole in the middle.

[xxxmicrobexxx@hotmail.com]

Fascinating.

And South America doesn't get them - except for a solitary example ??
Are there any theories about why that may be ?

I came to ask the same question...

[XgeoX]

Fascinating.

And South America doesn't get them - except for a solitary example ??
Are there any theories about why that may be ?

I came to ask the same question...

It’s interesting, I thought the reason why was the Southern Atlantic was too cold for the to form but according to NASA…

“ Vertical wind shears in the south Atlantic are too strong for hurricanes," Hood explains. Winds in the upper troposphere (about 10 km high) are 20+ mph faster than winds at the ocean surface. This difference, or shear, rips storms apart before they intensify too much…”

Maybe cold water has something to do with it but I am no wind shear expert!!!



Hang on cyclone kitty!

Eric

[JohnD]

Quote, " cyclones usually occur over water, which makes sense since evaporating warm water gives them energy. "

Elementary mistake, surely? CONDENSING vapour provides the typhoon's energy.

Or am I too picky, the water vapour has to be evaporated first, which occurs in tropical regions, the condensation occuring as the storm moves away from the Equator, and cools?

The lack on the west coast of South America could be due to the cold Humboldt Current. That on its east coast is strange but true, for a similar reason, low sea temperature. See: https://www.stratumfive.com/climate/sou ... spotlight/

John

[orin stepanek]

I noticed that there seems to be more typhoons (hurricanes} In
western Pacific than in the Athlantic: I thought we had it bad!

0100358.jpg (78.77 KiB) Viewed 13967 times

Awe; curious kitty; be careful!

[Chris Peterson]

Quote, " cyclones usually occur over water, which makes sense since evaporating warm water gives them energy. "

Elementary mistake, surely? CONDENSING vapour provides the typhoon's energy.

Or am I too picky, the water vapour has to be evaporated first, which occurs in tropical regions, the condensation occuring as the storm moves away from the Equator, and cools?

Well, it is the combination that matters, right? The system is a heat engine, with the evaporation/condensation cycle transferring energy from the ocean to the atmosphere where it is converted to kinetic energy. Energy can't be created, after all. Perhaps we should say that it is the warm water that provides the energy, and the other mechanisms just move it.

[bngooby@gmail.com]

Curious about the different colors used in the graph -- what do the blues vs. yellows represent.
BTW, love cyclone kitty!

[Fred the Cat]

Hurricanes and most tornados except for one odd duck. It almost flew too far south. Apparently some southern fowl do head north.

Proves we ducks must live in the northern universe.

[neufer]

Quote, " cyclones usually occur over water, which makes sense since evaporating warm water gives them energy. " Elementary mistake, surely? CONDENSING vapour provides the typhoon's energy.

Or am I too picky, the water vapour has to be evaporated first, which occurs in tropical regions, the condensation occuring as the storm moves away from the Equator, and cools?

Well, it is the combination that matters, right? The system is a heat engine, with the evaporation/condensation cycle transferring energy from the ocean to the atmosphere where it is converted to kinetic energy. Energy can't be created, after all. Perhaps we should say that it is the warm water that provides the energy, and the other mechanisms just move it.

Hurricanes Celia & Darby in the eastern Pacific (and the precursor to Hurricane Alex) in the Intertropical Convergence Zone. (Summer solstice: 2010)

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When (light) hot moist air rises above the oceanic thermal equator it continues to rise & remain warm by condensing into clouds, rain & eventually ice crystals in the towering tropical cumulonimbus clouds of the Intertropical Convergence Zone (ITCZ).

The oceanic thermal equator slowly tracks the Sun's annual seasonal cycle with a delay of about a quarter of a cycle (i.e., warmest ocean temperatures ~ fall equinox ~ peak cyclone season). Such delayed tracking drags the ITCZ north & south of the actual geographic Equator where at latitudes 5º (and higher) rotating ITCZ convergent surface winds can spin up into tropical cyclones.

New tropical cyclones are pushed westward by the subtropical Easterly Trade Winds until they are pulled up into the mid-latitude westerly winds (by subtropical anti-cyclones) where they dissipate due to wind shear and lack of warm ocean water.
.
.
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Hadley cells within an idealized depiction of the Earth's atmosphere

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<<The Intertropical Convergence Zone (ITCZ), known by sailors as the doldrums or the calms because of its monotonous windless weather, is the area where the northeast and the southeast trade winds converge. It encircles Earth near the thermal equator though its specific position varies seasonally. When it lies near the geographic Equator, it is called the near-equatorial trough. Where the ITCZ is drawn into and merges with a monsoonial circulation, it is sometimes referred to as a monsoon trough, a usage that is more common in Australia and parts of Asia.

The ITCZ appears as a band of clouds, usually thunderstorms, that encircle the globe near the Equator. When the ITCZ is positioned north or south of the Equator, these directions change according to the Coriolis effect imparted by Earth's rotation. For instance, when the ITCZ is situated north of the Equator, the southeast trade wind changes to a southwest wind as it crosses the Equator. The ITCZ is formed by vertical motion largely appearing as convective activity of thunderstorms driven by solar heating, which effectively draw air in; these are the trade winds. The ITCZ is effectively a tracer of the ascending branch of the Hadley cell and is wet. The dry descending branch is the horse latitudes. The location of the ITCZ gradually varies with the seasons, roughly corresponding with the location of the thermal equator. As the heat capacity of the oceans is greater than air over land, migration is more prominent over land. Over the oceans, where the convergence zone is better defined, the seasonal cycle is more subtle, as the convection is constrained by the distribution of ocean temperatures.

The ITCZ is commonly defined as an equatorial zone where the trade winds converge. Rainfall seasonality is traditionally attributed to the north–south migration of the ITCZ, which follows the sun. Although this is largely valid over the equatorial oceans, the ITCZ and the region of maximum rainfall can be decoupled over the continents. The equatorial precipitation over land is not simply a response to just the surface convergence. Rather, it is modulated by a number of regional features such as local atmospheric jets and waves, proximity to the oceans, terrain-induced convective systems, moisture recycling, and spatiotemporal variability of land cover and albedo.>>

[neufer]

Hurricanes and most tornados except for one odd duck.

It almost flew too far south. Apparently some southern fowl do head north.

• Typhoon Vamei was a northern equatorial fowl who flew Northwest:

Typhoon Vamei developed on December 26, 2001 at 1.4° N

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Typhoon Sarah developed on March 21, 1956 at 2.2º N

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Click to play embedded YouTube video.

<<Typhoon Vamei was a Pacific tropical cyclone that formed closer to the equator than any other tropical cyclone on record. The last storm of the 2001 Pacific typhoon season, Vamei developed on December 26 at 1.4° N in the South China Sea. It strengthened quickly and made landfall along extreme southeastern Peninsular Malaysia. Vamei rapidly weakened into a remnant low over Sumatra on December 28, and the remnants eventually re-organized in the North Indian Ocean. Afterward, the storm encountered strong wind shear once again, and dissipated on January 1, 2002. Vamei broke the previous record of Typhoon Sarah in the 1956 Pacific typhoon season, which reached tropical storm strength at 2.2º N. Due to a lack of Coriolis effect near the equator, the formation of Vamei was previously considered impossible.

Vamei developed in a vortex that appears every winter along the northwest coast of Borneo and is maintained by the interaction between monsoonal winds and the local topography. Often, the vortex remains near the coastline, and in an analysis of 51 winters, only six reported the vortex as being over the equatorial waters for four days or more. As the area in the South China Sea between Borneo and Singapore is only 665 km wide, a vortex needs to move slowly to develop. A persistent northerly wind surge for more than five days, which is needed to enhance the vortex, is present, on average, nine days each winter. The probability for a pre-existing tropical disturbance to develop into a tropical cyclone is between 10 and 30 percent. Thus, the conditions which resulted in the formation of Vamei are believed to occur once every 100–400 years.>>

Proves we ducks must live in the northern universe.

Click to play embedded YouTube video.

<<Ducks have a cosmopolitan distribution, and are found on every continent except Antarctica. Several species manage to live on subantarctic islands, including South Georgia and the Auckland Islands. Ducks have reached a number of isolated oceanic islands, including the Hawaiian Islands, Micronesia and the Galápagos Islands, where they are often vagrants and less often residents. A handful are endemic to such far-flung islands.

Some duck species, mainly those breeding in the temperate and Arctic Northern Hemisphere, are migratory; those in the tropics, however, are generally not. Some ducks, particularly in Australia where rainfall is patchy and erratic, are nomadic, seeking out the temporary lakes and pools that form after localised heavy rain.>>

[Sa Ji Tario]

Fascinating.

And South America doesn't get them - except for a solitary example ??
Are there any theories about why that may be ?

Coincidentally with the storm zones, there is a high-altitude jet stream that runs through the Pacific from west to east, runs through North America, the Atlantic, into Europe, crosses the Arabian peninsula and opens in two, one that closes the cycle on India and the other that runs through the Indian Ocean and part of the Pacific, both on the sides of the Earth's equator. Is it a coincidence?

[revloren]

Anyone remember the Pacific storm that headed east and appeared fizzle out of the coast of California?

[johnnydeep]

Curious about the different colors used in the graph -- what do the blues vs. yellows represent.
BTW, love cyclone kitty!

Wind speed. The "feathured map" link in the description takes you to the explanation:

This map shows the tracks of all Tropical cyclones which formed worldwide from 1985 to 2005. The points show the locations of the storms at six-hourly intervals and use the color scheme from Saffir-Simpson Hurricane Scale.

So, the bluer, the less the wind speed, and the redder, the greater the wind speed.

[donalgary]

I'd really like to see a four maps, each one for a five year period to see if there is a systematic change in the paths. Any suggestions?

[XgeoX]

I'd really like to see a four maps, each one for a five year period to see if there is a systematic change in the paths. Any suggestions?

NOAA has a yearly database with maps of the year’s hurricanes…

https://www.aoml.noaa.gov/hrd/hurdat/Da ... Storm.html

Eric

[Chris Peterson]

I'd really like to see a four maps, each one for a five year period to see if there is a systematic change in the paths. Any suggestions?

Each of the data sources used makes their raw data available in various GIS formats (like KML). You could produce such maps using the same techniques the author of this image used.

[neufer]

Anyone remember the Pacific storm that headed east and appeared fizzle out of the coast of California?

• Bovary, Mulva, Loreola, Celeste, Hest, Gipple...

The track and intensity of Elida, according to the Saffir–Simpson scale

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<<Hurricane Elida was the first hurricane of the 2002 Pacific hurricane season to reach Category 5 strength on the Saffir-Simpson Hurricane Scale. Forming on July 23 from a tropical wave, the storm rapidly intensified from a tropical depression into a Category 5 hurricane in two days, and lasted for only six hours at that intensity before weakening. It was one of only sixteen known hurricanes in the East Pacific east of the International Date Line to have reached such an intensity. Although heavy waves were able to reach the Mexican coastline, no damages or casualties were reported in relation to the hurricane.

The hurricane moved westward due to a high pressure ridge while undergoing two eyewall replacement cycles: the first was around peak intensity and was completed when the hurricane moved over cooler waters, and the second was a brief cycle shortly after the hurricane began to weaken. The last advisory was issued while the hurricane was west of Mexico, but it was not until the remnants were west of Los Angeles, California that they finally dissipated. Elida's rapid intensification and unsteady weakening after reaching its peak intensity caused large errors in the intensity forecasting of the hurricane. Although the intensity forecasts were off, the track forecasts were better than usual compared to the ten-year period prior to that year.>>

[asmacarthur_y]

Am interested to know more of the explanation behind the lone trail in the Northeast Pacific.

[bystander]

Am interested to know more of the explanation behind the lone trail in the Northeast Pacific.

Hurricane Guillermo (1997)

[neufer]

Click to play embedded YouTube video.

Am interested to know more of the explanation behind the lone trail in the Northeast Pacific.

• Hurricane Guillermo (1997)

[RJN]

Feedback indicates that the designation of "hurricane" in the Atlantic and "typhoon" in the Pacific has exceptions. Therefore, the text of the main NASA APOD has been updated to include the word "Usually" at the front of the second sentence. Also, the explanatory link https://gpm.nasa.gov/education/articles ... al-cyclone has been provided under the word 'Usually". I apologize for the oversight.

- RJN

[Fred the Cat]

Click to play embedded YouTube video.

Am interested to know more of the explanation behind the lone trail in the Northeast Pacific.

• Hurricane Guillermo (1997)

Living in Astoria, Oregon at the time, I got a “get out of school free” card for the Columbus Day Storm of 1962. And actually a few days more for the clean-up.

Never having been through such a storm before it was quite interesting but nerve-racking for my parents and grandparents. From my memory we only lost the windows from the front porch.

[D. Gus]

Your writer has a significant fact wrong and botched the explanation of why cyclones do not cross the equator.

First of all, the Coriolis effect is at it maximum at the equator, not zero as stated in the write-up. The force from Coriolis is proportional to (ω X r), where ω is the rotation speed and r is the axial distance from the center of rotation. Since the Earth turns on the axis that runs through the poles, the equator is at the maximum distance from this axis, so it gets the maximum Coriolis forces. Conversely, the polar regions have the least Coriolis forces.

The main reason that cyclones do not cross the equator is due to convection. The Earth's atmosphere has organized itself into a total of six convection zones: the north and south tropic zone, the north and south temperate zone, and the north and south polar zone. For the tropic zones, they start at the equator and nominally extend 30 degree north or south. The convection pattern goes like this: the maximum amount of heating occur at the equator so that air is moving vertically and at the temperate zone the air is coolest, causing the air to sink. For example in the northern tropic zone, as the hot rises it flows north. With Coriolis, this air is "pulled" to the west. The high part of the convention loop is what is know as the steering current. Since Coriolis is at the maximum at the equator, you can note that most of the northern storms start out travelling in a westerly to north-westerly direction.

One other thing I would like to mention, once a northern hemisphere storm hits the temperate zone, they all tend to take a right hand turn, and head in an easterly direction. This is very important to me, since I live in New Orleans, which is at 30 degrees north latitude. I have watched many storms hit Texas boomerang back at us.