Earth & Weather

Hurricanes form over warm ocean water and go by different names — typhoon or cyclone — in other parts of the world.

Tornadoes form beneath thunderstorms, and the United States records more of them than any other country.

The water cycle moves water between ocean, atmosphere, and land, driven mainly by evaporation and precipitation.

Erosion gradually wears away rock and soil, shaped over time by wind, water, and ice.

Climate change describes long-term shifts in weather patterns, driven in recent history by human greenhouse gas emissions.

El Niño periodically warms central Pacific waters, shifting weather patterns across much of the globe.

The jet stream flows fast near the boundary of air masses high in the atmosphere, shaping weather and flight times alike.

Lightning discharges built-up electrical charge in storm clouds and can heat surrounding air hotter than the Sun's surface.

Rainbows form as sunlight refracts and reflects inside water droplets, always appearing opposite the Sun.

The aurora borealis lights up the sky when charged solar particles strike Earth's atmosphere near the poles.

Metamorphic rock forms when heat and pressure transform existing rock without it fully melting.

Earth's atmosphere divides into layers such as the troposphere and stratosphere, with nearly all weather in the lowest layer.

Plate tectonics describes the slow movement of Earth's outer shell, reshaping continents over geological time.

Earthquakes release built-up energy along a fault and are measured with scales like the Richter or moment magnitude scale.

Volcanoes vent molten rock, ash, and gases, often clustering along the edges of tectonic plates.

Tsunamis, often triggered by undersea earthquakes, can race across an entire ocean basin at high speed.

The rock cycle describes how rock transforms between igneous, sedimentary, and metamorphic forms over vast timescales.

Continental drift proposed a single ancient landmass, an idea later explained more fully by plate tectonics.

The greenhouse effect traps heat near Earth's surface and, in its natural form, keeps the planet warm enough for life.

The ozone layer absorbs most harmful ultraviolet radiation, and a hole over Antarctica was traced to certain man-made chemicals.

Glaciers build up from compacted snow over long periods and store a large share of the world's fresh water.

Monsoons bring a distinct wet season to parts of Asia, driven by temperature differences between land and ocean.

Thunder comes from air rapidly expanding after being heated by lightning, and its delay can help estimate distance.

Earth's magnetic field, generated by molten iron in the outer core, shields the planet from much of the Sun's radiation.

The Richter scale expresses earthquake magnitude, with each whole number marking a tenfold jump in measured amplitude.

Sedimentary rock forms from compacted layers of sediment and often preserves fossils of ancient life.

Igneous rock forms as molten rock cools and solidifies, whether underground or after a volcanic eruption.