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What Causes Rain and How Clouds Are Formed

 

If you’ve never heard of rain, you may be wondering what causes it. This article will explain what causes rain, how clouds are formed, and how water drops collide with air. In addition, you’ll learn about the acidity of raindrops. If you want to understand rain and why it falls, read on! If you want to be able to predict it, you can also check out our article on the science of cloud formation.

Clouds

When the weather turns wet, clouds change from their typical hard, cloud-like appearance to soft and squishy shapes. These clouds are called cumulonimbus clouds. They contain large amounts of water in droplets. Once they reach a height of three kilometers or two kilometers, precipitation begins to form. The precipitation may be the result of colliding or coalescing large cloud drops, or it may be a mixture of both.
Air turbulence

Air turbulence is an annoying part of flying, but most of the time, it’s harmless enough for everyone to ignore. However, it can be deadly, with six people dying in the US alone since 1980 from turbulence. While it is rare, accidents during turbulence often happen when passengers are not buckled in. Luckily, aircraft are designed to withstand rough weather and turbulence.

Collision of water droplets

The colliding of water droplets during rain has several mechanisms. One of them is the effect of air streamlines. These streamlines bow out around the collector drop and carry the smaller collected drops around the larger drop. As the radii of the collector drop and the smaller collected drops increase in size, their effective cross-sectional area decreases. Because of this, larger drops are less likely to follow the air streamlines and instead collide with each other.
Acidity of raindrops

The acidity of raindrops can be measured using the pH scale. This scale ranges from zero to fourteen. The ideal pH level is seven, but rainwater falls closer to 5.5. Water vapor condenses around minute particles in the air when temperature falls. In order to fall as a raindrop, water must contain some amount of carbon dioxide, so that the water vapor can reach equilibrium with atmospheric carbon dioxide.

Drizzle

What is a Drizzle? A Drizzle is a thin layer of liquid that falls from the sky similar to rain, but the droplets are much larger. Drizzle can occur as a result of partial evaporation, but the difference is small enough to be ignored. Unlike rain, a Drizzle usually falls at a very gentle rate. Nevertheless, it’s important to know the difference between drizzle and rain, especially when it comes to weather conditions.
Unevenness of precipitation

The unevenness of precipitation measure quantifies the proportion of total precipitation that falls on wettest days of the year. The question this measure answers is: what proportion of total precipitation falls on the wettest N days of the year? Its goal is to be as easy to understand as possible. To calculate the measure, time series of daily accumulation of precipitation are sorted from highest to lowest. Then, the time series is normalized by total precipitation over the year. The cumulative amount of precipitation is then calculated as the number of wettest days of a year.
Size of raindrops

The size of raindrops is determined by their size distribution, also known as granulometry. This feature of raindrops varies throughout a thunderstorm, with the largest raindrops forming in a cloud with an equivalent diameter of about 5 millimeters. However, these large raindrops are rare and result from a warm rain process that causes hail to melt. Scientists used to believe that the raindrops collided and split up into smaller particles, but the current understanding is that the droplets are not physically colliding with each other.