The weather on Earth is always changing. One day it's cloudy, the next day it's sunny, and the day after - who knows? Meteorologists are scientists that can predict the weather. But how do they do it? What causes these changes in weather? The Footprint Reading Library" is the first non-fiction reading series for English language learners to present real-world stories in print, audio, and video. This series offers fascinating stories and facts from across the planet, and develops the language and skills needed to understand non-fiction writing. It offers a rich selection of engaging non-fiction, grouped into five themes: Incredible Animals, Fascinating Places, Remarkable People, Exciting Activities, and Amazing Science. One hundred individual readers are graded into eight levels - from Pre-Intermediate to Advanced. It ranges from 800 to 3,000 headwords