Children’s Illustrated World Atlas

Book Preface

Active Planet
Earth is a dynamic planet that is always changing its form. Heat generated by nuclear reactions deep below the surface creates hugely powerful currents that keep Earth’s rocks on the move, triggering earthquakes and volcanic eruptions. Meanwhile, solar energy striking the planet in different ways creates currents in the air, driving the atmospheric turmoil of the weather. This changes with the seasons and from place to place, creating an enormous range of climates and habitats for the most dynamic element of all—life.

WHERE MOVING PLATES MEET
The boundaries between the plates are volcanic earthquake zones. The plates move very slowly, pulling apart at divergent boundaries. This allows hot rock below to melt, erupt, and cool to form new crust— especially at the spreading rifts that form mid-ocean ridges. Meanwhile at convergent boundaries, one plate slides beneath another, pushing up mountain ranges and making volcanoes erupt. Other volcanoes erupt over hot spots in the mantle below the crust.

THE SEASONS
Earth spins on a tilted axis, so as it orbits the Sun once a year the North Pole points towards the Sun in June and away from it in December. This means that in regions north of the tropics it is summer in June but winter in December—and the opposite to the south of the tropics. Near the Equator it is always warm, but there are annual wet and dry seasons.

JUNGLE AND DESERT
Concentrated sunlight near the Equator heats Earth’s surface, warming the air above. The warm air rises, carrying moisture with it. This forms huge clouds that spill tropical rain, fueling the growth of rainforests. The dry, cooling air then flows north and south and sinks over the subtropics, creating deserts. Similar air circulation patterns affect the climate in the far north and south.

ANNUAL RAINFALL
Some parts of the world get far more rain than others. The wettest regions are mainly rainforest zones, where year-round rain and warmth promote lush plant growth. Regions of moderate rainfall are naturally forests and grasslands, although much of this land is now used for farming. The driest regions may be too dry for many plants to grow, creating deserts—but they also include some northern forest zones and polar tundra.