Cryology is the study of cold and freezing. It covers a wide range of topics, from how cold affects living things to how ice forms and what it is made of. Cryologists may work in fields as diverse as engineering, biology, medicine, atmospheric science, and materials science.
The word “cryology” comes from the Greek words for “cold” (kryos) and “study” (logos). The study of cryology began in the 18th century with the work of Swedish scientist Carl von Linné on plants that grow in cold climates. In the 19th century, scientists began to study how animals adapt to cold weather. In the early 20th century, researchers started using microscopes to study how ice crystals form.
Today, cryologists use a variety of techniques to study everything from frozen DNA to quantum computers. They also develop new ways to use cold temperatures for medical treatment and industrial processes.
Most matter exists in one of three states: solid, liquid, or gas. When matter changes from one state to another—for example, when water freezes into ice—it undergoes a physical change. A physical change is a change in the matter’s size, shape, or state without changing its chemical composition. Freezing is an example of a phase change; other examples include melting and vaporization (or boiling). Changes between phases are driven by changes in temperature or pressure—or both. For example, increasing temperature always causes melting (a solid-to-liquid phase change), while decreasing temperature always causes freezing (a liquid-to-solid phase change). However, whether increasing or decreasing pressure causes vaporization depends on the substance: For most substances (such as water), increasing pressure inhibits vaporization while decreasing pressure promotes it; but for some substances (such as carbon dioxide), exactly the opposite is true! Understanding these relationships between temperature/pressure and phases is critical for many applications: If you want something frozen—say, food or tissue samples—you need to know how lowering temperature affects them; if you want something unfrozen—like metal parts cooled for machining—you need to understand how raising temperature will help achieve that goal; finally