How do environmental kills charge the Ultimate Meter?

Solution 1:

It would appear as though the amount of ultimate charge is granted based on the current health of the target when the kill is registered by the death-zone at the bottom of the pit.

Test case 1: Winston (500HP) Environmental

Test case 2: Winston (~240HP) Damage+Environmental

Test case 3: Winston (500HP) Full Damage

Test case 4: Winston Primal Rage (1000HP) Environmental

Test case 5: Tracer (150HP) Environmental

Test case 6: Tracer (120HP) Punch+Suicide

We can see from these clips that, negating the over time ultimate gain, the amount of charge gained is consistent with the total damage dealt, not including any measure of overkill.

For reference: For every 15 points of damage dealt by or as a result of Pharah's actions, 1% ultimate charge is granted. This means 33.3% charge for Winston, 10% for Tracer (consistent with what we see above).