While asking another question about Jormungandr, the Snakebot of Doom, a point was made that it is so big and hot that it might produce its own weather effects. To that end:

Jormungandr is 446 metres in diameter, weighs 1.486 billion metric tons, has a body that is cylindrical for 7480m, and then tapers down to a point over a further 669m, the tail matching with a similarly shaped mouth. Its armour is made from Tungsten-depleted Uranium alloy plates with a smooth surface coating of Boron Carbide, at the surface appearing to be overlapping scales around five metres long and half a metre thick, much like the scales of a snake. Most importantly to this question, it is driven by shape-memory-alloy 'muscles' that have an operational temperature of around 97°C/207°F, and it has a similar surface temperature in air due to its cooling requirements, but the skin temperature would be much lower in water.

In order to power its huge demand for energy, it is equipped with six hot-fusion reactors, each of which is capable of producing enough energy to power its shape-memory-alloy muscles or its entire complement of rail guns.

While it is rolling sideways, when steamrolling a city, it moves at around 5kph / 3mph. However, it is capable of slithering in a serpentine manner at up to 20kph, and can roll into a hoop and travel at around 100kph on a level surface. It is also capable of travelling underwater, at up to 30kph rolling or 15kph slithering.

In its travels from its construction site beneath the highest point of the Antarctic ice cap to the sea, it rolled at high speed, then travelled along the mid-Atlantic ridge (an area with high levels of geologic and thermal activity), and then surfaced off New York City, which it is presently flattening.

The question:

In each of its movement regimes, both above and below water, what effect might Jormungandr have on local and global weather patterns?

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    $\begingroup$ A quick Fermi estimation based on the heat needed to keep the 97°C surface temperature in 10°C water gives me an energy usage in the order of Terawatts. This equals around the energy that the sun shines on an area of ~70km times 70 km. I guess that should have some impact on at least the local weather. $\endgroup$
    – Christoph
    Apr 18, 2017 at 9:36
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    $\begingroup$ What does it keep from melting INTO the ice in the Antarctic? It might tunnel trough the ice by melting it. Creating its own pocket of nearly boiling water. When it comes out, it will change the water temperature notably. $\endgroup$ Apr 18, 2017 at 10:12
  • $\begingroup$ @Christoph, The surface temperature is close to 97°C in air, due to the poor heat conductivity of air and the need for cooling the snakebot's internals. In water, the skin temperature would be much lower. $\endgroup$
    – Monty Wild
    Apr 18, 2017 at 22:12
  • $\begingroup$ @Flummox, When being built in the Anarctic, its muscles were inactive, and hence didn't need to be so hot. When it was brought to operational status, that's a different matter, but melting a tunnel through ice would still be too slow given the massive, observsble heat bloom it would cause. $\endgroup$
    – Monty Wild
    Apr 18, 2017 at 22:16

1 Answer 1


A Snakebot that is perfectly cylindrical would have a surface area of about 28 million square meters. Let's round down to 20 because cones.

Metals have a heat flux coefficient of maybe 5-8 watts per m^2 K. It's about 70 K above background, or about 10 GW dumped to atmosphere all the time.

Thunderstorm scientists measure air energy in CAPE, which is complex to calculate but is about 5000 J/m^3 at worst. Over my head today it's about 300 J/kg. A microcell thunderstorm is about ten kilometers on every side, and heating that much air would take ~days.

In sum: It could trigger rain if rain was in the forecast, but it can't cause rain on its own.


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