Water can exist in any of the three classical states of matter—solid, liquid, or gas. The state depends on the intermolecular forces that attract molecules to each other and the temperature, which measures the average molecular kinetic energy. Lowering the temperature reduces the kinetic energy. At 0 °C, hydrogen bonds cause the molecules to pack together in a lattice structure, allowing little movement and forming solid ice. Raising the temperature increases the kinetic energy, breaking the hydrogen bonds and other intermolecular forces. At 100 °C, the molecules become far apart so that these forces are disrupted, and the molecules are free to move at high speeds to form water vapor. When the temperature decreases, the water vapor changes back from its gaseous to its liquid form through a process called condensation. Water vapor can also transition directly into a solid in a process called deposition, which is how snowflakes are created. The reverse process, sublimation, occurs when ice directly vaporizes, as in the freeze-drying of many foods in a vacuum.