The Great Red Spot on Jupiter and the numerous Great White Spots on Saturn are storm systems that encircle the globes and last for decades, centuries in Jupiter's case. These are formed on Gas Giants though, with atmospheric compositions that would not support Human life, or pretty much any life that we would recognise. So what little I have been able to glean as to the cause of these storms does not hold up for my scenario.
I'm building an earth-sized world with an Oxygen-rich 'breathable' atmosphere. Currently my Northern Hemisphere is still 'fluid' and can be changed to accommodate any features I care to include. I've been thinking of including a giant 'eternal' storm that slowly circles the globe.
Is a storm lasting decades-centuries possible on a non-Gas Giant Planet?
What conditions do I need to create a large 'eternal' storm?
It doesn't have to be on the size-scale of the Saturn/Jupiter Storms. I'm happy for it to spawn little storms. I'm happy for it to have little storms merge into it and 'feed' it. It can wax and wane in strength. I'm happy for it to circle the globe taking many years for one 'revolution'.
I see two possible storm routes:
- circles the globe, crossing oceans and continents in a 'straight' line
- travels across the ocean and partly over the continent. Due to Coriolis force it then circles back over the ocean, before hitting the other side of the continent and then being turned back into the ocean again, again to Coriolis force. Effectively like a gigantic atmospheric gyre.
I'm hoping for a generic answer that others can also use, so I'm tempting fate and not including my own world map. But if it really becomes necessary I can add it. Remember, I can change my world's northern hemisphere to fit the requirements of the story. Tell me what I need and I will make the changes...
Currently I have 'mostly' open ocean (~80%) with a single large continent in the Northern Hemisphere. It's about as wide as North America from New York to San Francisco. It is a hot, dry desert with a large Rockies/Andes equivalent mountain range running horizontally W-E, across the very top blocking the arctic winds from bring snow (and associated springmelt) and cold temperatures to the desert region. This can change if necessary, although I would really like to keep the large desert.
Things that cannot be changed:
- My planet is Earth sized (not a gas giant) and within the Goldilocks zone.
- It supports complex life.
- My planet has planetary rings and several moons.
- The storm cannot bring about complete atmospheric collapse and kill off all the plants and animals. If this happens, I will go without! Thank you very much.
Note: Yes, climate is complex. But I'm asking if this sort of storm is possible on a non-gas giant planet, without killing off all the life on the planet. As well as looking for a generic list of conditions/features that can set me on the path to creating this storm. Also, please note, I'm not asking if this storm would be possible on Earth.