I want to make a heat map of an Earth-like planet for a poster just like the one on the picture below. (The map doesn't need to follow Earth's geography, spaces for land and ocean can be randomised). I tried using Photoshop to render clouds and create random shapes from there, then stacking layers on top with smaller shapes and different colours for each thermal threshold. But the colours did not blend in well with each other and it looked like a topography map rather than a heat map. Is there any way this can be done easily in Illustrator (Photoshop is also welcome but I only understand the basics).
Thank you very much to anyone who could kindly help.