Plants can also survive extreme cold conditions brought forth during the winter months. Many plant species located in northern climates can acclimate under these cold conditions by supercooling, thus these plants survive temperatures as low as −40 °C (−40 °F). Although this supercooling phenomenon is poorly understood, it has been recognized through infrared thermography. Ice nucleation occurs in certain plant organs and tissues, debatably beginning in the xylem tissue and spreading throughout the rest of the plant. Infrared thermography allows for droplets of water to be visualized as they crystalize in extracellular spaces.