Raynaud's Phenomenon. Raynaud's phenomenon (also referred to as Raynaud's syndrome or Raynaud's disease) affects the bodily extremities, most commonly the hands and feet. On exposure to cold or stress, the blood vessels at the extremities constrict or narrow, restricting the flow of blood; this is called vasoconstriction. This condition has been visualized using thermal infrared which allows us to see thermal energy or radiation more commonly referred to as heat. The hand affected with Raynaud's is on the right, the other hand is unaffected. This image shows both hands after exposure to cold water for two minutes. The unaffected hand (on left) warms considerably quicker and begins to emit higher levels of radiation (heat) whilst the affected hand continues to emit lower levels. The different colors in the images represent different levels of thermal energy being emitted from the skin's surface. In this image the yellow and orange colors show a high level of thermal energy and the blue a low level.