| Some of the extraterrestrial material could be incorporated into polar stratospheric clouds over Antarctica and sediment out of the lower stratosphere. |
| The extremely cold temperatures of the stratosphere during the polar winter enable the development of polar stratospheric clouds. |
| That triggered vast polar stratospheric clouds, some of them as big as the continental United States. |
| The Arctic stratosphere temperature remained warmer than normal for much of the winter, limiting the formation of polar stratospheric clouds that act as a catalyst in Arctic ozone depletion. |
| These polar stratospheric clouds form only in regions of very low temperature and as a result the clouds only exist in winter stratospheric polar regions. |
| Such a cooling could increase the formation of polar stratospheric clouds, causing Arctic ozone depletion to become even more severe. |
