How does the water cycle affect the salinity of the ocean?

Actually it's more like the salinity affecting the water cycle.

Water evaporation is happening constantly, and the rate at which it's evaporating or its volatility that is to say depends on the pressure of the atmosphere.

Water boiling point happens when the pressure of the atmosphere is equal to the vapor pressure of the liquid.

Water has some kinetic energy, given that its at a certain temperature. What's holding the water in its liquid state are the hydrogen bonds. (look up dipole-dipole intermolecular forces) When you apply the let's say heat to it, they kinetic energy is increasing (the water molecules are moving faster and faster) and these hydrogen bonds are broken and the vapor pressure goes up and it goes from liquid to gas. The other factor in keeping the water in it's liquid state is the pressure of the atmosphere keeping the water from just becoming the atmosphere itself.

Water doesn't have to "boil" at 100 degrees C. The pressure of the atmosphere at sea level is 760 torr. But let's say you were in Utah where elevation is higher and the atmospheric pressure is less, you'd find that water boils at 95 degrees C.

So the lower the atmospheric pressure, the more water is going to go into "boil mode." Now that you know that, understand that ocean water isn't pure water. There is salt in it. NaCl. Those hydrogen bonds that hold water together are stronger with the Na ions. I'm not going to get into intermolecular forces that's a subject to long to explain here, but know its a huge factor. Because those bonds of salt water are stronger, it's harder for the molecules to escape into the gaseous state. The temperature needs to be higher than 100 degrees C to boil salt water.

Just think if the salinity constantly increases in our oceans, and it is. That means that it's harder for the water to escape into the gaseous state. So there you have it, the salinity effects the water cycle.

P.S not my words