Maharashtra Board Class 9 Geography Chapter 5 Precipitation PDF Download

Precipitation

Can You Tell?

Observe the pictures given below. A sentence describing the picture has been given. You describe the picture by writing some additional sentences. Discuss the questions.

The blades of grass look like this on winter mornings.

From where does the water on the blades of grass come?

Snow is found everywhere in the winters in Kashmir.

Why isn't snow found in our surroundings?

Generally, it rains between June and September in our region.

How do the rain droplets form? Can you tell?

In London, there is fog like this till the afternoons in the winters.

Why don't we have fog like this till afternoons in the winters in our region?

Sometimes hailstones destroy the standing crops in the fields.

Why don't we get hailstones frequently?

Teacher's Note

In India, we see dew on grass in winter mornings, just like in the picture. This water comes from water vapour in the air.

Exam Trick

Remember: Dew = water droplets on cold objects. Frost = frozen dew. Both happen in winter mornings on grass and leaves.

Points to Remember

Dew is water droplets that form on cold surfaces in the morning.
Snow falls in very cold places like Kashmir and mountains.
Rain happens when water droplets in clouds become heavy and fall down.
Hailstones are ice balls that form high in the clouds.

70.8% part of the earth's surface is full of water. The distribution of this water is very uneven. At some places, the water storage is limited while it is ample at other places. We see/experience the different forms of condensation as shown in the pictures above and in figure 5.1. These forms of condensation occur due to the water vapour in the atmosphere.

As the atmospheric conditions change, we see changes in the forms of condensation. On winter mornings, we find dew. In areas located at higher altitudes, snowfall occurs; while it rains in other places. Some places experience dense fog while some experience hailstones suddenly and face crop destruction.

Precipitation

Water falls in the solid or liquid state from the clouds to the ground. Snow, hailstones, rainfall are the major forms of precipitation.

Teacher's Note

Precipitation means water falling from clouds to earth in any form. In your city, you see rain. In mountains, people see snow.

Exam Trick

Remember three main types: Rain (liquid), Snow (solid ice), Hail (ice balls). All are precipitation because water falls from sky.

Points to Remember

Precipitation is water falling from clouds in solid or liquid form.
The three main types are rain, snow, and hailstones.
Dew and frost form near the earth's surface.
Fog is made of tiny water droplets floating in air.
70.8% of earth has water but it is spread unevenly.

Snow

When the temperature in the atmosphere falls below the freezing point, water vapour directly turns into snowflakes. This is called sublimation. Here, the vapour in the form of gas transforms into solid snow. Precipitation in the form of solid particles of snow is known as snowfall. In high latitudinal and temperate regions, snowfall occurs at the mean sea level while in tropical areas, snowfall occurs at places located higher than the snowline altitude.

As snow is in the solid form, it does not flow like water. Layers of snow get deposited. When the snow accumulates on a large-scale, then the transport and communication system of that area collapses. People living in those regions have to protect themselves from frostbite. When the snow melts, the region gets water.

Teacher's Note

Snowfall happens only in very cold places. In Kashmir, heavy snow blocks roads and trains. People have to dig snow to move.

Exam Trick

Remember: Sublimation = gas turning directly to solid (water vapour to snowflakes). This happens when temperature goes very low.

Points to Remember

Snow forms when water vapour changes directly to solid snowflakes.
This process is called sublimation.
Snow does not flow like water - it stays in layers.
Too much snow blocks roads, trains, and communication.
Frostbite is a danger to people in snowy areas.

Hail

When there is lot of heat on the earth's surface, the upward air flow blows at a greater speed. Because of this upward flow, the temperature of the air reduces and the condensation of the water vapour takes place. Dark clouds are formed. Because of the upward movement of air, these water droplets go to a higher altitude. Here, solidification of these droplets occur and hailstones are formed.

As hailstones are heavy, they fall towards the ground, but because of the frequent upward flow of air, they are repeatedly taken upwards. Here, a new layer of snow encapsulates the hail. This happens quite a few times. Hence, concentric layers are formed while the hail grows in size. These big heavy hailstones fall rapidly to the ground because of gravity. We call the precipitation of this type as hail showers. Because of hail, crops may get destroyed and loss of life and property may also occur.

Teacher's Note

Hailstones are ice balls that fall during summer storms in India. They can damage crops and hurt people. They form high in the sky where it is very cold.

Exam Trick

Remember: Hail = layers of ice like an onion. It goes up and down many times, getting thicker each time, then falls as ice ball.

Points to Remember

Hail forms when water droplets freeze into ice at high altitude.
Upward air currents take hailstones up and down many times.
Each time they go up, a new ice layer covers them.
Hailstones grow bigger and bigger like onion layers.
Hail damages crops and can harm people and animals.

This is a preview of the first 3 pages. To get the complete book, click below.