cascade d'énergie

CONT: ... many weather phenomena occur on the 'mesoscale' ... Mesoscale is believed to play an important role in transferring energy from the large scale down to the small scales. ... Energy Cascade. As we go down scales, we see finer and finer structures. Many of these structures are due to certain types of instabilities that inherently limit the size and duration of the phenomena. Also, there exist exchanges of energy, heat, moisture and momentum among all scales. Example: A thunderstorm feeds off convective instabilities ... created by e.g., synoptic-scale cyclones. ... The thunderstorm in turn can produce tornadoes ... Strong winds in the tornado creates turbulent eddies which then dissipate and eventually turn the kinetic energy into heat. Convective activities can also feed back into the large scale and enhancing synoptic scale cyclones. Most of the energy transfer in the atmosphere is downscale - starting from differential heating with latitude and land-sea contrast on the planetary scales. (Energy in the atmosphere can also transfer upscale). We call the energy transfer among scales energy cascade.