What does the water cycle have to do with the weather?

The water cycle has everything to do with weather. Weather is practically run by the water cycle. Almost all types of weather consist of water.
Tornadoes, hurricanes, thunderstorms,blizzards, and rain all have to do with the water cycle. Tornadoes form when wet, hot air meets dry, cool air. Hurricanes form from differences in air and water tempurature. Thunderstorms are made of clouds, and blizzards are just frozen water.
The water cycle keeps life going. Without it, we would all die. I am glad that the water cycle will always be cycling.

What is the main power source behind the water cycle?

The main power source that drives the water cycle is the sun. It is not the only source, but it is the most important. And this is what it does:

The sun heats the land and ocean, causing water to evaporate, sending it into the air, making clouds. When the water droplets become too heavy, they fall to the ground as precipitation( either rain, hail, sleet, or snow). When these fall they either get consumed by plants or animals, or runoff into bodies of water. Finally, the plants precipitate and the animals pee, and all the water evaporates, going through the cycle again.

The sun effects almost all of earth's cycles (excluding the rock cycle, which is powered by convection). This is how the sun effects the water cycle. They cycle thats involved in almost every cycle.

How does the water cycle effect clouds?

The sun heats water on the ground or in the ocean, causing it to evaporate. This evaporated water, or water vapor, when it condenses, is what we see as clouds. There are many types of clouds.
Cirrus and cirrostratus are high-level clouds. These usually form at above 20,000 feet (6,000 meters) and are usually made of tiny ice crystals. High-level clouds are usually thin and white in appearance but, when seen on the horizon at sunrise or sunset, can display a magnificent array of vivid colors. Altocumulus and altostratus are mid-level clouds. Mid-level clouds usually appear between 6,500 and 20,000 feet (2,000-6,000 meters). These clouds are usually formed from water droplets but can be formed from ice crytals as well if the tempuratures are cold enough. Altocumulus clouds usually look like parallel band or rounded masses. A characteristic that distinguishes an altostratus cloud from a cirrostratus cloud is that parts of altostratus clouds are usually shaded. Lower-level clouds such as nimbostratus clouds are usually under 6,500 feet (2,000 meters ). They are usually dark and are formed from water droplets, and are usually accompanied by an average to light precipitation. Fair weather cumulus clouds usually have a life span of 5 to 40 minutes. These clouds are distinguished by their flat bases and their distinctly shaped tops (the clouds we used to think looked like rabbits or something). These fair weather clouds can turn into powerful cumullonimbus clouds, which bring powerful thunderstorms.
Even though these clouds are very diverse in their forms they all have one thing in common, they are all made of water vapor and are extremely important in the water cycle. Because if their were no rain, the water couldn't cycle. Then we would all die.