Pressure, Winds, Storms, and Cyclones

About this chapter

Pressure, Winds, Storms, and Cyclones is Chapter 6 of Class 8 Curiosity. Through Megha and Pawan's school bags with broad and narrow straps, students meet pressure as force per unit area, with the SI unit newton per metre-squared (N/m^2) also called the pascal (Pa). Activity 6.1 with two glass pipes of unequal diameter shows that liquid pressure depends on column height, not weight — which is why overhead water tanks are placed high. Activity 6.2 with a punctured bottle shows liquids exert pressure on container walls in all directions, and the broad base of a dam withstands horizontal water pressure near the bottom. Activity 6.3 with the inverted paper-plate-and-chart-paper setup, and Activity 6.4 with the rubber sucker, demonstrate atmospheric pressure — the air column over 15 cm x 15 cm exerts a force of about 2250 N, balanced by the pressure inside our bodies. Activities 6.5 and 6.6 with connected and adjacent balloons show air moves from high-pressure to low-pressure regions, and that high-speed winds reduce air pressure, which is why roofs of weak houses can be blown off. Storms, thunderstorms (lightning + thunder), local thunderstorms like Kalboishakhi in Bengal/Bihar/Jharkhand, Bordoisila in Assam and mango showers in Kerala, Karnataka and Tamil Nadu, and cyclones that form over warm ocean waters with the calm eye of the cyclone at the centre, complete the chapter. The Amphan cyclone of 2020 with peak winds of 270 km/h and the role of the India Meteorological Department (IMD) anchor the Indian context. CTET Paper 2 Science tests this chapter on pressure-area reasoning, water-column height, atmospheric-pressure facts, high-speed-wind effects, lightning safety, thunderstorm formation steps and cyclone structure. The four tests — Practice 15, Quiz 15, Hard 15, Mastery 30 — cover these ideas at exam depth.