Editing Skein of Worlds:The Material Plane (section)

=== The Elemental Spheres ===
The elemental spheres, or planets, (usually) exist as a balance of the four elements. Each planet has an overall balance, but few planets are uniform. Different areas of a planet can have slightly different balances of the elements. This can be more obvious in some places than others. One of the clearest examples is a hot, dry desert where there is too much fire and not enough water. In places of especially high concentrations of one element vortices into the Elemental Tempest can form. A planet that is heavily unbalanced towards one element might gain a minor elemental trait. Rarely a planet may be lacking all four elements. Such a place would be a lifeless ball of cold, grey dust with a thin, unbreathable atmosphere.

==== Earth ====
Earth provides the solid ground. It is the most stable element, and rarely fluctuates much. Areas with too little earth are dusty or flowing. Quick sand or tar pits would be a localized example of this. Areas with too much earth would be very rocky and mountainous. Earth vortices tend to form in deep caves.

==== Air ====
Air provides, well... air. Air fluctuates a good deal as the winds come and go. Areas with too little air tend to make breathing difficult. This might manifest in any number of ways, from a simple lack of air, to stagnant air, to a lot of dust or water vapor suspended in what air there is. Areas with too much air tend to be very windy. Air vortices tend to form in large, high clouds.

Air exists even underground and underwater. Areas underwater with too little air can't support sea life very well. Areas underwater with too much air tend to manifest as underwater fountains of bubbles and the like.

==== Water ====
Water provides the oceans, lakes, rain and all other forms of moisture. Water doesn't fluctuate very rapidly, but its changes are sometimes pronounced, bringing dry days and rain, or drought and floods. Areas with too little water are simply dry. Areas with too much water tend to have a lot of lakes and heavy rains. Even areas underwater can lack water, even if that's hard to put into words. Such areas would be similar to areas that lack air aboveground, but are overall pretty rare. Water vortices tend to form in the deep ocean rifts.

==== Fire ====
Fire provides warmth. Areas with too little are cold, and areas with too much are hot, but fire is the most unstable element. It can fluctuate wildly even within a single day. Fire vortices mainly form in volcanoes.