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Why does dry ice sublime instead of forming a liquid at ordinary atmospheric pressure?

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Diagram showing four physical states of matter: solid with tightly packed molecules, liquid with loosely packed molecules, gas with widely spaced molecules, and plasma with free electrons and nuclei, each labeled with descriptions and an arrow indicating increasing energy. — phase States of matter.

Dry ice, which is solid carbon dioxide, sublimes at ordinary atmospheric pressure because its triple point—the specific temperature and pressure at which the solid, liquid, and gas phases of a substance coexist in equilibrium—occurs at a pressure higher than standard atmospheric pressure.12

In a phase diagram, the state of a substance is determined by its temperature and pressure. For most substances, the triple point exists at a pressure well below one atmosphere, allowing them to exist as a liquid under normal conditions. However, because the triple-point pressure of carbon dioxide is approximately 5.2 bars, it cannot exist as a stable liquid at the lower pressure of the normal atmosphere. Consequently, when dry ice is exposed to standard atmospheric pressure, it bypasses the liquid phase entirely and converts directly from a solid to a gas, a process known as sublimation.1234