Look up at the sky. Is it raining or sunny? Are there big, puffy clouds that look like marshmallows, or dark, angry clouds threatening sleet? No matter how the sky appears, you are looking at Earth’s lower atmosphere, the realm that is studied by the science of meteorology. Meteorology concerns itself with the science of atmospheric properties and phenomena—science that includes the atmosphere’s physics and chemistry.

Meteorologists are often thought of as people who forecast the weather. And some meteorologists certainly do that! Predicting the weather is a complicated process, which requires both sophisticated new tools and some old-fashioned techniques. Meteorologists are observers and researchers. They note the physical conditions of the atmosphere above them, and they study maps, satellite data, and radar information. They also compare various kinds of weather data from local, regional, and global sources.

Beyond weather forecasting, meteorology is concerned with long-term trends in climate and weather, and their potential impact on human populations. An important area of meteorological research these days is climate change and the effects it may cause.

Many people wonder why the study of the atmosphere is called meteorology. The name comes from the ancient Greeks. In about 340 B.C.E., the Greek philosopher Aristotle wrote a book called Meteorologica, which contained all that was known at the time about weather and climate. Aristotle got the title of his book from the Greek word “meteoron,” which meant “a thing high up” and referred to anything observed in the atmosphere. That term stuck through the centuries, so experts on the atmosphere became known as meteorologists.