Class 8 Science — Winds, storms and cyclones

Trace a wind back to a difference in air pressure, and follow the chain from a rising column of warm air to a thunderstorm and a cyclone.

Name: ________________________

1.Put the steps that end in a flash of lightning back into the order the chapter gives them.
- The insulating property of air breaks down
- A bright flash of lightning is seen
- The ground below becomes positively charged
- Charge separates, leaving the lower part of the cloud negative
- Strong winds rub water droplets against ice particles
2.Match each name to what the chapter says it is.
- Storm
- Thunderstorm
- Cyclone
- Eye of the cyclone
- a spinning system of clouds, winds and rain around a very low-pressure centre
- the calm centre, where the pressure is at its lowest
- a storm that also brings lightning and thunder
- strong winds accompanied by rain
3.You are caught outdoors as a thunderstorm arrives. Sort these against the chapter's advice.
Groups: Safer during lightning · To be avoided during lightning
- Sheltering inside a car
- Crouching down in a low-lying open area
- Lying down flat on the ground
- Standing under a tall tree
- Using an umbrella with a metallic rod
4.A lightning conductor is a metallic rod fixed to a building, pointed at the top and buried deep in the ground at the bottom. What is it for?
- a) To give electric charge an easy path into the ground
- b) To stop lightning forming in the clouds above the building
- c) To attract the charge away from the ground into the sky
- d) To store the charge safely inside the building
5.Lightning heats the air around it very rapidly. What does that produce?
- a) Hail, as the heated air freezes on cooling
- b) Thunder, as the air expands and makes a loud sound
- c) Rain, as the heated air condenses
- d) A second flash a moment later
6.Why is it safer to leave doors and windows open during a storm with high-speed winds?
- a) It lets the wind blow straight through, so it cannot push on the walls
- b) It raises the pressure inside the house well above the pressure outside
- c) It cools the house, and cool air presses down on the roof
- d) It lets the pressure inside and above the roof even out, so there is less difference to lift the roof
7.A cyclone that has come ashore gradually weakens. Why?
- a) The Earth rotates more slowly over land than over sea
- b) Buildings on land block the wind and slow it down
- c) Its source of warm moist air from the ocean has been cut off
- d) The land is colder than the sea, so it freezes the cyclone
8.The region of lowest pressure at the centre of a cyclone, where the wind is calm while the surrounding region is battered, is called the ___ of the cyclone. Give the one word.

Answer key — Class 8 Science — Winds, storms and cyclones

1. 1. Strong winds rub water droplets against ice particles 2. Charge separates, leaving the lower part of the cloud negative 3. The ground below becomes positively charged 4. The insulating property of air breaks down 5. A bright flash of lightning is seen
2. Storm → strong winds accompanied by rain; Thunderstorm → a storm that also brings lightning and thunder; Cyclone → a spinning system of clouds, winds and rain around a very low-pressure centre; Eye of the cyclone → the calm centre, where the pressure is at its lowest
3. Crouching down in a low-lying open area → Safer during lightning; Sheltering inside a car → Safer during lightning; Standing under a tall tree → To be avoided during lightning; Using an umbrella with a metallic rod → To be avoided during lightning; Lying down flat on the ground → To be avoided during lightning
4. a) To give electric charge an easy path into the ground
5. b) Thunder, as the air expands and makes a loud sound
6. d) It lets the pressure inside and above the roof even out, so there is less difference to lift the roof
7. c) Its source of warm moist air from the ocean has been cut off
8. eye