Cold-Core Low

A cold-core low is a cyclone aloft with a pool of cold air sitting at high altitude in the troposphere and no frontal structure, growing stronger with height under the thermal wind relationship because colder air has less room between pressure surfaces, which increases wind speed higher up. Its isolated cold air pool creates a center of minimum atmospheric thickness, and because temperature and pressure gradients line up similarly at any given radius from the center, the system behaves in a barotropic way. Cut off from the main westerly wind belt that would otherwise steer it, a cold-core low moves erratically, tends to produce cloud and rain mainly during the day as surface heating destabilizes the air, and can spawn tornadoes near its center or help spin up polar lows and tropical cyclones.