4 ms·

A lot. Look up Hadley cells. https://groups.seas.harvard.edu/climate/eli/research/equable/hadley.html https://groups.seas.harvard.edu/climate/eli/research/equ

by btilly 3y ago

A lot. Look up Hadley cells. https://groups.seas.harvard.edu/climate/eli/research/equable/hadley.html https://groups.seas.harvard.edu/climate/eli/research/equable... Warm air rises near the tropics, rotating with the Earth. It then goes towards the temperate zone, still rotating with the Earth to form the jet stream. It then falls, creating the trade winds as it slows down. It then is sucked back towards the tropics, creating a reverse trade wind because it is only going as fast as the temperate zone. And then it rises, completing the cycle. The prevailing wind in both temperate zones and the tropics is therefore due to the Earth's rotation.

dredmorbius 3y ago
Hadley cells determine wind patterns but not the energy content of the wind, to any appreciable degree, which comes from solar flux. Wind energy is solar energy once removed. Wave energy is solar energy twice removed (solar -> wind -> waves).
- btilly 3y ago
  Yes, the energy driving the entire system comes from the Sun. But the fact that it takes the form of wind rather than rising/falling columns of air has to do with the rotation of the Earth. Ditto for hurricanes. Hurricanes turn rising/falling air into cycling air into hurricane force winds because the Earth rotates. But the energy for it came from the Sun. Often removed by another factor, Sun warms ocean, ocean drives the storm.
  - dredmorbius 3y ago
    Wind is due to Earth's rotation much in the same way that airflow through ducts is due to the ducts. Earth's rotation directs the energy imbued by the Sun, much as ductwork directs airflow through a structure imbued by blower motors. But neither wind, nor ducted airflow, originate from, are driven by, or otherwise exhaust the Earth's rotation, or the containing ductwork, respectively. (Yes, there are frictional forces of the atmosphere against the Earth's surface. On balance these probably net out, as atmospheric flows at large scale are balanced, else we'd end up with a zone of vacuum and one of infinite pressure on the Earth's surface.) The original question was "How much [wind] is due to earth's rotation?", in the context of whether or not wind is a renewable energy resource. Given that wind is fundamentally driven by solar flux, wind is renewable, and it is not driven (vs. directed or influenced) in any meaningful way by Earth's rotation.
- pyaamb 3y ago
  if we harvest wind do we still deplete waves?
  - dredmorbius 3y ago
    In theory, yes. In practice, wave action is caused by fetches across hundreds or thousands of kilometres of sea surface, and even offshore wind farms tend to be located within a few km of shorelines. As with other impacts described, the potential interactions with bird life (strikes, kills, behavioural disruption), and of the artificial-reef effects of offshore turbine foundations and anchorages (probably largely positive) would all but certainly dominate these by many orders of magnitude.

by btilly 3y ago

dredmorbius 3y ago

Hadley cells determine wind patterns but not the energy content of the wind, to any appreciable degree, which comes from solar flux. Wind energy is solar energy once removed. Wave energy is solar energy twice removed (solar -> wind -> waves).

btilly 3y ago
Yes, the energy driving the entire system comes from the Sun. But the fact that it takes the form of wind rather than rising/falling columns of air has to do with the rotation of the Earth. Ditto for hurricanes. Hurricanes turn rising/falling air into cycling air into hurricane force winds because the Earth rotates. But the energy for it came from the Sun. Often removed by another factor, Sun warms ocean, ocean drives the storm.
- dredmorbius 3y ago
  Wind is due to Earth's rotation much in the same way that airflow through ducts is due to the ducts. Earth's rotation directs the energy imbued by the Sun, much as ductwork directs airflow through a structure imbued by blower motors. But neither wind, nor ducted airflow, originate from, are driven by, or otherwise exhaust the Earth's rotation, or the containing ductwork, respectively. (Yes, there are frictional forces of the atmosphere against the Earth's surface. On balance these probably net out, as atmospheric flows at large scale are balanced, else we'd end up with a zone of vacuum and one of infinite pressure on the Earth's surface.) The original question was "How much [wind] is due to earth's rotation?", in the context of whether or not wind is a renewable energy resource. Given that wind is fundamentally driven by solar flux, wind is renewable, and it is not driven (vs. directed or influenced) in any meaningful way by Earth's rotation.
pyaamb 3y ago
if we harvest wind do we still deplete waves?
- dredmorbius 3y ago
  In theory, yes. In practice, wave action is caused by fetches across hundreds or thousands of kilometres of sea surface, and even offshore wind farms tend to be located within a few km of shorelines. As with other impacts described, the potential interactions with bird life (strikes, kills, behavioural disruption), and of the artificial-reef effects of offshore turbine foundations and anchorages (probably largely positive) would all but certainly dominate these by many orders of magnitude.