When water droplets in clouds become too heavy to remain in the air, precipitation happens. Precipitation comes in four varieties. The sort of precipitation that falls is determined by the temperature. Runoff is the final stage of the water cycle. It begins with rainfall or snowfall. When it melts or washes away, it returns water to the atmosphere. Ocean waters are constantly evaporating and condensing with surrounding air temperatures and pressures. This process moves large amounts of water vapor from the ocean into the atmosphere where it can form more clouds.
At night time when it is cold out, ice forms on any liquid surface, including rainwater in a pipe or container. In the morning when it is warm out, this ice will melt if not removed. This is why you should not leave any containers of water outside over the night-time-ice-will-form part of the water cycle!
The process by which water is recycled within the Earth's environment is called the hydrologic cycle. Water flows through each phase of the cycle: evaporation, transpiration, runoff, and back to evaporation again. Water is also returned to the atmosphere as vapor. So both air and water are always moving around the globe, but only water is visible.
Water discharged from clouds in the form of rain, freezing rain, sleet, snow, or hail is referred to as precipitation. It is the major link in the water cycle that allows atmospheric water to be delivered to the Earth. The majority of the precipitation falls as rain. However, some precipitation may fall as frozen droplets (ice) or vapor (snow). Snow and ice can accumulate on land or sea, forming glaciers or ice caps, respectively. Water vapor can accumulate into clouds or liquid water can collect into lakes or other bodies of water.
When rain drops hit a surface they spread out into a thin layer of water molecules. This layer becomes increasingly saturated with each drop that falls, until it reaches its capacity to hold any more water. At this point, it begins to drip again! Most rain drops are small enough to pass through solid objects such as plants or buildings without being absorbed. But sometimes large particles are trapped along with the water droplets. If this occurs indoors, you will need a dehumidifier to remove the moisture smell caused by these particles.
The amount of precipitation that falls as snow vs. as rain depends on temperature. Snow is formed when cold air flows over warmer ground, causing its crystals to grow larger. Ice is just plain old frozen water and can form at any temperature if there is enough pressure. Hail is small ball-like pellets of ice that can occur in clusters or single files.
The water that falls as rain or freezes is called liquid water. Water that enters the atmosphere as vapor is called dry air. Dry air can't support any more moisture so any vapor it does contain will eventually be turned into ice.
Hail is a small solid particle of ice that forms in clouds and becomes large enough to be seen without a microscope. Hail occurs when droplets of water within clouds grow large enough for their surface tension to force them apart. This separation causes them to lose contact with the cloud layer below which allows gravity to pull them down towards the ground.
The term "hail" also refers to the damage done by these particles to human-made objects. Hailstones are very hard when first formed and become more fragile as they age. The closer together hailstones are found, the higher the wind speed was when they formed.
Hail can cause serious damage to vehicles, especially if it's a large rock and the driver doesn't see it coming. It can also do considerable damage to crops and other property not directly in the path of the storm.
Step 3 of the Water Cycle: Water returns to the Earth as precipitation. When water droplets become too heavy, they fall back to Earth as rain! This is referred to as precipitation because it can come in three forms: rain (liquid water), snow (frozen water), and hail (big pieces of frozen water). Rain falls from clouds that form when warm, moist air rises and is cooled by cooler air below. Snow and hail are forms of precipitation that occur when clouds pass over a cold surface such as the ground or a frozen lake. When this happens, the heat from the sun melts some of the ice crystals that make up the cloud and causes them to drop like stones.
Rain is one of the four main forms of precipitation. The others are sleet, snow, and hail. All four types of precipitation occur throughout the year, but they are most common during the winter months when there is more energy in the atmosphere than at other times of the year.
As water vapor in the air reaches 32 degrees Fahrenheit, it becomes liquid water and falls as rain or snow. The amount of water vapor in the air changes daily as hot air aloft heats up and is replaced by cooler air from below. This replacement leads to morning and evening showers or storms. If there is no change in temperature between the air above and below, then there will be daytime heating and cooling, but not enough to lead to precipitation.
The water vapor then cools and condenses at a predetermined height to produce clouds. Water condenses to produce clouds, but when too much water accumulates, the clouds become heavy, and water falls from the sky in the form of rain, snow, or hail. This process is called evaporation and precipitation. Evaporation is the loss of water vapor into the air, while precipitation is the accumulation of liquid water from the atmosphere or ocean. The water that falls as rain or melted ice enters lakes and oceans, which are then evaporated by solar radiation back into the atmosphere where it re-forms into clouds and starts all over again.
The water cycle can also be described as the flow of water from the earth's surface to the sea and back again. Clouds collect water from the earth's surface and release it back into the atmosphere through precipitation. All water on the earth is part of this cycle, even the water found in rocks and minerals. The only thing preventing it from returning to space is the fact that it is contained within Earth's gravity field.
When clouds pass over hot surfaces like those of volcanoes or power stations, they lose some of their moisture through evaporation. This makes more dense clouds which can lead to fogging up of windshields and other glass surfaces. Fog is visible water vapor suspended in air. When clouds reach the ground, they can form rain, snow, or hail depending on how strong they are.