When the timeline is changed, any timeline, a wave of temporal energy is released. This temporal energy goes through time and space like pressure waves in water. As it moves through space-time the energy is released altering the timeline in its wake. This is a natural process to restore balance and equilibrium to a timeline.
The larger the alteration and more energy is released and thus the more powerful the wave. A temporal wave will progress through space-time at a predictable rate, though to the observer in 3-dimensional space this is not apparent and alterations can be erratic depending on a host of variables. Some things are more static between possible timelines and possible outcomes than others making a temporal wave appear to travel through space at different speeds when in reality the older an event is, the sooner it will be altered and thus the sooner directly related events will be altered relative to someone observing alterations from a point in 3-dimensional space.
Temporal waves are graded by their power level on a natural logarithmic scale similar to how decibels are measured. The incoming temporal field energy is measured against the base-line field energy of an area and reduced to an integer. This measures how powerful temporal shields will need to be to overcome the incoming temporal wave.
Broken Into Grades
The grade of a wave is then also relational to the severity off the change in the timeline at the origin. Thus it is also a measure of how much change is required to restore balance relative to the original timeline. In other words, the grade of a temporal wave also measures how much of a place and time remain the same and how much changes after a wave passes. Mathematically this translates to a wave intensity relating to alterations curve being asymptotic.
Grades are broken down to 1 through 24 with a grade 25 wave being impossible to mathematically obtain. A grade 25 wave would thus be of infinite intensity. Such waves are mathematically impossible to survive as they would require infinite energy in a temporal field. Even if an infinite amount of energy could be produced somehow the generators, conduits, and other physical distributors of this energy would need infinite capacity. Such a wave is generated when nothing remains of the original timeline. This kind of wave is called an Infinity Wave.
In theory, should an Infinity Wave be encountered, resisting it could have disastrous effects. Such as ripping holes in spacetime and doing irrevocable damage to multiple realities. The only way to survive an Infinity Wave is to keep it from being created at the source before it inevitably alters the timeline at your origin. Example is, if you're from 2380 you would possibly be able to travel back through time to the origin of an infinity wave (though how possible such travel might be is a hotly debated subject in temporal mechanics) and then would need to stop the wave from occurring before that wave impacted and altered 2380.
When a temporal wave impacts temporal shields the waves energy grows exponentially and proportionally to the severity of the original event. It draws this new energy from the surrounding space-time causing a wake not unlike a stone or tree in a river process a wake as the water has to go around it to pass. I the shields can withstand the bombardment of temporal energy until the energy dissipates then the shields remain intact and the space inside the shields is protected from the alterations in the timeline - i.e. a leaf from a tree that no longer exists, continues to exist. This also generates temporal energy in waves out from the source (the leaf will continue to exist and thus the temporal energy radiates outward after the original wave and alters the timeline to make this so).
To maintain temporal shields a core producing temporal energy to power the shields and the shield generators producing the artificial temporal field must output temporal energy which equals or surpasses the energy they are being bombarded with. This creates temporal currents around the shields causing momentary anomalies in space-time. These currents flow around the object and spread outward from it creating a storm effect. Random bits of the timelines (both original and altered) coalesce in small bursts and link together before falling apart again. The storm effect can continue around temporal shields even after the wave has passed.