Water Cycle and Earth's Internal Structure
The water cycle is like Earth's circulatory system, constantly moving water around the planet. It starts with evaporation from oceans and lakes, then transpiration from plants adds more water vapor to the air. This vapor cools and forms clouds through condensation, eventually falling back as precipitation.
Earth's internal structure has three main layers that get hotter as you go deeper. The crust is the thin outer layer we live on - it's only 2-75 miles thick and contains silicon, aluminum, and calcium. The oceanic crust forms ocean floors, while continental crust makes up the continents.
The mantle is the largest layer, making up 80% of Earth's mass. At about 900°C, it's hot enough that rock flows like thick liquid! Convection currents in the mantle cause hot magma to rise, cool, and sink back down, which drives changes on Earth's surface.
Remember: The core has two parts - a liquid outer core made of melted iron and nickel, and a solid inner core where extreme pressure keeps metals squeezed together despite the intense heat.