NCERT Class 8 Science Chapter 6

Winds are caused by differences in air pressure. When one region of Earth's surface is heated more than another, the air above it becomes warm and rises, creating a low-pressure area. Cooler, denser air from a high-pressure region flows in to fill the gap — this moving air is wind. NCERT Class 8 Chapter 6 explains this in detail.

A cyclone forms over warm ocean water. The warm, moist air rises rapidly, creating a low-pressure centre. Surrounding air spirals inward and upward due to the pressure difference and Earth's rotation. As moisture condenses, it releases heat that intensifies the storm. The result is a powerful rotating storm with strong winds and heavy rain.

A cyclone is a large weather system (hundreds of kilometres wide) that forms over warm ocean water with spiralling winds around a calm centre called the eye. A tornado is a narrow, violently rotating column of air (metres to kilometres wide) that forms over land from severe thunderstorms. Tornadoes are more intense but smaller than cyclones.

Sea breeze blows from sea to land during the day — land heats faster than sea, warm air over land rises, and cooler sea air moves in. Land breeze blows from land to sea at night — land cools faster than sea, so the relatively warmer air over the sea rises and cooler air from land moves towards the sea.

Safety measures include: listening to weather warnings and evacuating if told to do so, staying indoors away from windows, not going near the coast, not touching fallen power lines, storing drinking water and emergency supplies, and following official instructions. NCERT Class 8 Chapter 6 emphasises the importance of early warning systems.

At higher altitudes there is less atmosphere above you, so the weight of air pressing down is less. This means air pressure decreases as you go higher. That is why mountaineers sometimes carry oxygen cylinders and why aircraft cabins are pressurised.