list_for_each_entry(co2_cloud_t, pos, &env->cloud_head, list)
clouds[i++] = pos;
qsort(clouds, n_clouds, sizeof(clouds[0]), cmp_clouds_gt);
list_for_each_entry(co2_cloud_t, pos, &env->cloud_head, list)
clouds[i++] = pos;
qsort(clouds, n_clouds, sizeof(clouds[0]), cmp_clouds_gt);