Author: Arshia, Learner at The Integral School. A partly independent project that explores rain.
The content of this assignment is presented under the following subheaders
- Origin of the word Rain
- How does rain occur
- Effects of rain
- Different kinds of rain
- Prediction of rain
- Study of rain
- The smell that comes after rain
- Why is rain seasonal
- Rain patterns of the world
- Does it rain on other planets
- Greek rain God
This project is about rain. I have written how rain occurs, effects of rain and tried to look at some interesting questions about rain. I have also drawn diagrams to make it more interesting.
Origin of the word Rain
The word has its origins in the proto germanic language. They called it “Reg” which meant “Moist, wet”. Soon, in Latin they called it Reg which meant to wet or to make moist. Soon in old English they called rain “regn” and now it is called rain.
Why and how does rain occur?
Clouds are formed by the water that evaporates from the seas, rivers and lake. The water vapour goes up because it is hot and it turns into droplets at the higher parts of the sky as it is cooler there. The water droplets collide because of the movement of air and join together. When they join, the droplets become heavier and the air can’t hold them anymore. They fall as rain.
Water vapour needs a surface to condense on. Water vapour condenses on aerosols. Aerosols are small microscopic dust particles (which are: pollen, pollutants, man made fire, volcanic eruption, etc). When water vapour condenses on aerosols to become water droplets, they are called CCN (cloud condense nuclier). In polluted areas it rains less because there are lot of dust particles for the water vapour to condense. If there is less pollution, then the water vapour condenses on top of each other and becomes heavier. Then they fall as rain.
Few clouds are darker than others because the thicker clouds will block sunlight from reaching us. If the cloud is thin, it will not block sunlight.
Effects of rain
Flood- Floods happen in different ways.
Tropical cyclones can cause floods that happen really fast, in big areas and happen around coastal areas. Another type of flood is where the ground water rises after heavy rain for a long time. Rivers start overflowing and the flood happens along the river.
Another type of flood is flash flooding. It happens in one episode of heavy rain. It happens in mountain regions where all the water collected over mountains falls to the river quickly and the people in the river get washed away.
Drought is where it doesn’t rain for a long time. It happens in places where people eat what they grow from their farms. They don’t get from outside and if there is a drought, they suffer.
Different types of rain
Drizzle: falls down slower than rain and has smaller droplets than rain
Snow: Snow starts when small ice crystals join together and get heavy. When they are falling, they are called snow. It snows only in cold weather as snow needs low temperatures.
Hail: In a thunderstorm cloud, the ice crystals falling can get caught in updrafts and get carried upwards. The ice crystals that are falling down get joined to the one going up and become bigger. This cycle keeps on happening until they become very heavy and they fall as big balls of ice or hail.
Dew: When water vapour cools down on grass, it is called as dew.
Mist: When water vapour cools close to the ground on aerosols, it is called mist
Fog: A thick mist is a fog
Sleet : Sleet is a mixture of ice and rain
Frost : When dew becomes frozen it turns into frost.
How do you predict rain
You can predict rain by observing nature. Like when it gets humid, bees go back to their hives and cows sit on grass. Radar takes pictures by a satellite above the atmosphere of the earth to see the way the clouds are, to predict rain. Clouds get dark and it gets very windy, so we know it is going to rain soon.
The study of rain is called meteorology. Meteorologist studies weather that includes rain. They study day to day variations of the atmosphere.
What is the smell that comes after rain?
The smell that comes after rain is called petrichor. Per means stone and ichor means blood of the gods. The actual meaning of petrichor is the blood of stones because they found a yellowish oil in the rocks and dry soil. When it rains, the water washes the oil away and the scent is released into the air. The yellowish oil is responsible for the smell. The oil comes out by the pressure of the water that tries to get in the rocks. The water gets in and pushes the oil out. The oil spreads by the wind.
Why is rain seasonal?
Weather is the day to day changes in the temperature and moisture. Example: The weather of Hyderabad is sunny. Climate is the temperature and moisture for a long period of time. Example: Hyderabad has a rainy climate.
The sun heats up the air and it goes straight into the troposphere and leaves low pressure down below. Once the air cools down, it falls into a different place as high pressure because the earth rotates. To even out, the high pressure and low pressure, the high pressure air moves to the low pressure area. This movement is called wind or air currents.
Ocean currents are wide bands of water like a river that moves around from hot to cold places and back. It affects the climate. The cold currents reduce rainfall because there is no moisture above the currents. The hot currents are opposite and you will get heavy rainfall.
The rain from the high pressure area moves to the low pressure area and the clouds move with the air. So, there is less rain in high pressure area than low pressure area.
Rain patterns of the world
It rains all year in a range of 0 to 5 degrees around the equator. It rains in the summer and is dry in the winter around the 10 degrees area. There us slight summer rains around the 20 degree area and dry all year around the 30 degree area. There is slight winter rain around the 40 degree area, and dry summers and winter rains around the 50 degree area. It rains all through the year in the 60 degrees area. In the poles there us less rain. Rain patterns are caused by the wind, ocean currents and the rotation of the earth.
Does it rain on other planets?
It rains diamonds in Jupiter and Saturn
It rains sulphuric acid in Venus
Zeus is the weather God of Greek mythology. His symbols are thunderbolt, bull, oak and eagle. He was the head God because he was the weather God. Weather is important to grow crops etc.
Zeus got his thunderbolt from Cyclops because he helped them defeat Croons (he is evil father) and the Titans. Zeus would give good weather if he was happy and bad weather if he was angry. You had to pray to him to make him happy.