Can Tidal Wave disperse Fog Cloud?

Question

Hi I play Tritons (in D&D 5E) and they have this neat trait called Fog Cloud.

You create a 20-foot-radius sphere of fog centered on a point within range. The sphere spreads around corners, and its area is heavily obscured. It lasts for the duration or until a wind of moderate or greater speed (at least 10 miles per hour) disperses it.

Is there more I'm missing from this where Fog Cloud can be dispersed by other spells than "Wind" based spells? I was arguing with the other players because the DM had decided that Tidal Wave now can remove Fog Cloud. Since Create/Destroy Water can disperse a Fog Cloud, would this mean that Tidal Wave destroys it too?

Tidal Wave description:

You conjure up a wave of water that crashes down on an area within range. The area can be up to 30 feet long, up to 10 feet wide, and up to 10 feet tall. Each creature in that area must make a Dexterity saving throw. On a failed save, a creature takes 4d8 bludgeoning damage and is knocked prone. On a successful save, a creature takes half as much damage and isn’t knocked prone. The water then spreads out across the ground in all directions, extinguishing unprotected flames in its area and within 30 feet of it, and then it vanishes.

This says nothing about dispersing fog, so do we just assume it does?

Edit: I know there are other spells that can disperse Fog Cloud but I saw no Water spells like Tidal Wave listed.

Answer 1

Rules as written, tidal wave does not disperse fog cloud

As written, the fog cloud spell:

lasts for the duration or until a wind of moderate or greater speed (at least 10 miles per hour) disperses it.

There is nothing in the tidal wave spell that suggests that it causes a wind or disperses clouds of any kind, whether caused by fog cloud or something else.

Rulings not rules

It's the DM's job to make sure in your particular game that the game is playable, and they presumably had specific reasons for the ruling they made.

It's not clear from your description what the DM's reasoning was for allowing tidal wave to disperse fog cloud, but while the spell does not say it, it's not completely crazy that tidal wave's wave of water disperses a cloud.

This question discusses spells that will end the effect. It notes that thunderwave could, based on DM fiat, disperse the fog. The logic is perhaps similar to your DM's reasoning, although perhaps not all DMs would agree.

Practical effects

It's not clear from your question what class or level you are, but it's worth noting that fog cloud is a concentration spell, and since you can only have one concentration spell in effect at a time, you may find that you have many other choices available to you.

At 3rd level tritons can cast gust of wind and at 5th they can cast wall of water, and these are also concentration spells, as are many, many others.

You may find at you progress in levels that the practical effect of tidal wave canceling fog cloud is not all that significant.

Next steps

If you aren't satisfied with the DM's ruling, the best thing is to discuss it with them.

As a player, I find it frustrating when things don't work the way I expect, but once I find out how it's going to work in the future, then I can make plans based on that, even if I'm not completely happy. Hopefully you can do the same.

Sometimes I find a new angle to pursue, based on the DM's ruling, and maybe it's even better. That's always satisfying.

As a DM, I want to find the solution that makes the most sense for the game I'm running, and balances the various competing issues, and results in the most fun for everyone. Again, consistency is good, so that players know what to expect.