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There's a lot of weather on Earth, and a lot to learn about it. Scientists who study weather are called meteorologists or atmospheric scientists. Meteorologists know that the three ingredients needed to make weather are air, heat from the sun, and water. Those simple elements, in different quantities, can create snowstorms, rainbows, heatwaves, hurricanes, pretty clouds, tornadoes, and floods. More than two thirds of Earth is oceans of salt water. If all of the water on Earth were poured into 100 large buckets, 97 of the buckets would be salty ocean water. Ocean water keeps temperatures for islands steady throughout the year. Deep water moves slowly in currents. A scientist who studies oceans is an oceanographer.

Since the planet has land, water, ice, and mountains, and it is unevenly heated by the sun every day, the atmosphere is constantly in motion to try to equalize air pressure, moisture, temperature, and even electricity in air. The sun drives wind and the water cycle to create weather.

alaska landscape

The sun is the source of energy and heat for planet Earth. Energy from the sun travels as radiation, an average of 93 million miles through space, to reach us. That energy mostly passes through our atmosphere to reach and warm the ground and oceans. The ground quickly warms the air. The oceans store a tremendous amount of heat but also release some of it to warm the air.

Since the planet rotates, we get day and night. The planet can be divided into the northern hemisphere and the southern hemisphere, with the equator separating the two halves. Earth orbits the sun on a tilted axis, and that tilt is what causes seasons. At different times of the year, the hemisphere that is tilted toward the sun has the sun higher in the sky, with more direct and intense rays, and more hours of daylight. That would be summer. When one hemisphere has summer, the other has winter. A scientist who studies the sun and other stars and planets is an astronomer.

Air is a gas. It can change shape and move around like a fluid. When air warms, it expands and becomes lighter, or less dense, and that’s how hot air balloons can float. Air holds moisture and allows it to move around the planet. Cool air takes up less space and sinks. Air is everywhere but you can’t see it. Moving air is called wind. Air is more than oxygen. It is nitrogen, and many other gasses mixed together. Aside from holding water vapor, air also holds dust, pollen, and other particles.


Water can be invisible as water vapor, a gas. At other times we see water floating as clouds of tiny droplets or crystals of ice. Water can be liquid falling as rain, or solid ice falling as hail. On Earth, water can be in all three phases at the same time. The sun heats it to make it move and change weather and control climate. Water changes phase from ice to liquid to gas to create clouds, precipitation, and storms. Water is in the sea, in the air, and in the ground. In the water cycle, water goes through evaporation, condensation, and precipitation. A scientist who studies the movement of water on Earth is a hydrologist. Without water, we could not live on Earth.

Follow the Weather Science Library dropdown menu on this Weatherthings® website to explore and learn about the many types of weather and the field of meteorology.