Vanessa cardui migrations take place at high altitude, which explains why these migrations are seldom witnessed. "V. cardui" is known for its distinct migratory behavior. In California, they are usually seen flying from north to northwest. These migrations appear to be partially initiated by heavy winter rains in the desert where rainfall controls the growth of larval food plants. Painted lady migration patterns are highly erratic and they do not migrate every year. Some evidence suggests that global climatic events, such as el Niño, may affect the migratory behavior of the painted lady butterflies, causing large-scale migrations. Based on experimental data, the
Black and white been used to light for color. By shooting in black-and-white, the filmmakers did not have to rent lighting equipment. The movie "Pi" is filmed entirely in black-and-white, with a grainy effect until the end. In black-and-white still photography, many photographers choose to shoot in solely black-and-white since the stark contrasts enhance the subject matter. Some formal photo portraits still use black-and-white. Many visual-art photographers use black-and-white in their work. As a form of censorship when movies and TV series are aired on Philippine television, many gory scenes are shown in black-and-white. Sometimes the exposure of innards or other scenes too