5 ms·

> The Prosser report outlines one of the primary reasons for the increase in CAT events as the intensification of the jet streams, driven by the warming of the

by thiel 2y ago

> The Prosser report outlines one of the primary reasons for the increase in CAT events as the intensification of the jet streams, driven by the warming of the planet. As global temperatures rise, the temperature gradients between the equator and the poles become more pronounced, strengthening the jet streams and increasing the likelihood of turbulence . I was under the impression that, as the poles are MORE affected by global warming, the jet stream is becoming weaker? is that incorrect?

badcppdev 2y ago
Got some references?
- mcmcmc 2y ago
  They are cited in TFA https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2023GL103814 https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/202...
the_sleaze_ 2y ago
You might be thinking of the Gulf Stream, which is an oceanic current and definitively weakening, rather than the jet stream, which is an air current.
- quakeguy 2y ago
  Exactly, air currents are becoming stronger with warmer conditions, but the gulfstream being a water current it is expected to become weaker.
- rob74 2y ago
  To muddle things even further, there is a (jet) aircraft manufacturer called Gulfstream (https://en.wikipedia.org/wiki/Gulfstream_Aerospace https://en.wikipedia.org/wiki/Gulfstream_Aerospace). ...but I fully agree with the rest of your comment.
  - buildsjets 2y ago
    Not all Gulfstream aircraft are jets. Mine certainly isn’t. Piston powered, burns avgas, spins a propeller, goes around 130 knots.
- HPsquared 2y ago
  The jet stream is also driven by temperature differences. Same with most wind and weather, it's all various forms of heat engine. (Edit: though apparently the additional moisture in the Tropics more than counteracts any reduction in temperature difference: see link in Retric's comment)
- wongarsu 2y ago
  The jet stream is getting stronger (and its path becomes more erratic), but the reasoning provided in the article is simplified to the point of being wrong. The projected warming at the North Pole is much stronger than the projected warming at the equator, decreasing the temperature gradient. However the moisture carrying capacity of air increases exponentially with temperature. Since the equator starts warmer, a given change in temperature has a bigger effect on moisture carrying capacity. It turns out that heating up the equator by one degree Celsius and the North Pole by 2 degrees Celsius increases the moisture capacity gradient, despite the temperature gradient dropping. And that increasing moisture capacity gradient strengthens the jet stream. (at least that's the intuitive reason they were probably going for. In reality there are many factors and a good bit of "if we simulate it this keeps happening")
  - BlueTemplar 2y ago
    Thanks for the detailed explanation. But I also thought that it was the jet stream getting weaker that caused it to meander more (which sounds like it could increase CAT events ??), which we seem to be observing ??
konschubert 2y ago
That’s also what I read: The poles warm FASTER than the equator. Thus, the global temperature gradients are getting smaller. And as a result, not only does the Jetstream weaken: as a result, weather patterns become more stable which leads to greater continuous periods of draught or flooding.
- coldtea 2y ago
  jetstream != gulf stream
  - HPsquared 2y ago
    Jet stream is also driven by temperature differences, like basically all weather. Heat engines.
    - Retric 2y ago
      It’s a heat engine but more than just temperature changes are occurring. “The new study, by University of Chicago Professor Tiffany Shaw and NSF NCAR scientist Osamu Miyawaki, uses climate models to show that climate change intensifies this density contrast because moisture levels for air above the tropics will increase more than above the poles.” https://news.ucar.edu/132935/jet-stream-winds-will-accelerate-warming-climate#:~:text=The%20study%2C%20in%20Nature%20Climate,faster%20than%20the%20average%20wind https://news.ucar.edu/132935/jet-stream-winds-will-accelerat....
      - HPsquared 2y ago
        I guess it's like someone putting water on the coals in a sauna and the people feel a huge wave of heat due to the increased heat transfer, even though they've literally cooled down the coals.
      - HPsquared 2y ago
        Fair enough, I guess it's a pretty non-linear system!
polar_low 2y ago
That is correct, as a longer term trend at least while paradoxically, we are also seeing periods of record strength in the Jet Streams. The truth is there are many oscillations and teleconnections(themselves being impacted by global warming) which influences this temperature gradient on a local/seasonal basis. QBO, El Nino/La Nina and mountain torque events to name a few can move and shift heat at the tropopause in a short period of time and is why we see this wider variance at both ends of the spectrum.
photochemsyn 2y ago
I think the seasonality of the polar environment is a critical factor - while warming is expect to decrease the average equator-to-pole temperature gradient (as all models predict faster polar warming than equatorial warming by a large margin), winter is still winter as the polar axis is tilted, so steep atmospheric gradients are expected over that seasonal period.

by thiel 2y ago

badcppdev 2y ago

Got some references?

mcmcmc 2y ago
They are cited in TFA https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2023GL103814 https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/202...

the_sleaze_ 2y ago

You might be thinking of the Gulf Stream, which is an oceanic current and definitively weakening, rather than the jet stream, which is an air current.

quakeguy 2y ago
Exactly, air currents are becoming stronger with warmer conditions, but the gulfstream being a water current it is expected to become weaker.
rob74 2y ago
To muddle things even further, there is a (jet) aircraft manufacturer called Gulfstream (https://en.wikipedia.org/wiki/Gulfstream_Aerospace https://en.wikipedia.org/wiki/Gulfstream_Aerospace). ...but I fully agree with the rest of your comment.
- buildsjets 2y ago
  Not all Gulfstream aircraft are jets. Mine certainly isn’t. Piston powered, burns avgas, spins a propeller, goes around 130 knots.
HPsquared 2y ago
The jet stream is also driven by temperature differences. Same with most wind and weather, it's all various forms of heat engine. (Edit: though apparently the additional moisture in the Tropics more than counteracts any reduction in temperature difference: see link in Retric's comment)
wongarsu 2y ago
The jet stream is getting stronger (and its path becomes more erratic), but the reasoning provided in the article is simplified to the point of being wrong. The projected warming at the North Pole is much stronger than the projected warming at the equator, decreasing the temperature gradient. However the moisture carrying capacity of air increases exponentially with temperature. Since the equator starts warmer, a given change in temperature has a bigger effect on moisture carrying capacity. It turns out that heating up the equator by one degree Celsius and the North Pole by 2 degrees Celsius increases the moisture capacity gradient, despite the temperature gradient dropping. And that increasing moisture capacity gradient strengthens the jet stream. (at least that's the intuitive reason they were probably going for. In reality there are many factors and a good bit of "if we simulate it this keeps happening")
- BlueTemplar 2y ago
  Thanks for the detailed explanation. But I also thought that it was the jet stream getting weaker that caused it to meander more (which sounds like it could increase CAT events ??), which we seem to be observing ??

konschubert 2y ago

That’s also what I read: The poles warm FASTER than the equator. Thus, the global temperature gradients are getting smaller. And as a result, not only does the Jetstream weaken: as a result, weather patterns become more stable which leads to greater continuous periods of draught or flooding.

coldtea 2y ago
jetstream != gulf stream
- HPsquared 2y ago
  Jet stream is also driven by temperature differences, like basically all weather. Heat engines.
  - Retric 2y ago
    It’s a heat engine but more than just temperature changes are occurring. “The new study, by University of Chicago Professor Tiffany Shaw and NSF NCAR scientist Osamu Miyawaki, uses climate models to show that climate change intensifies this density contrast because moisture levels for air above the tropics will increase more than above the poles.” https://news.ucar.edu/132935/jet-stream-winds-will-accelerate-warming-climate#:~:text=The%20study%2C%20in%20Nature%20Climate,faster%20than%20the%20average%20wind https://news.ucar.edu/132935/jet-stream-winds-will-accelerat....
    - HPsquared 2y ago
      I guess it's like someone putting water on the coals in a sauna and the people feel a huge wave of heat due to the increased heat transfer, even though they've literally cooled down the coals.
    - HPsquared 2y ago
      Fair enough, I guess it's a pretty non-linear system!

polar_low 2y ago

That is correct, as a longer term trend at least while paradoxically, we are also seeing periods of record strength in the Jet Streams. The truth is there are many oscillations and teleconnections(themselves being impacted by global warming) which influences this temperature gradient on a local/seasonal basis. QBO, El Nino/La Nina and mountain torque events to name a few can move and shift heat at the tropopause in a short period of time and is why we see this wider variance at both ends of the spectrum.

photochemsyn 2y ago

I think the seasonality of the polar environment is a critical factor - while warming is expect to decrease the average equator-to-pole temperature gradient (as all models predict faster polar warming than equatorial warming by a large margin), winter is still winter as the polar axis is tilted, so steep atmospheric gradients are expected over that seasonal period.