Mount Hood's last major eruption occurred in the 1790's not long before Lewis and Clark's expedition to the Pacific Northwest. In the mid-1800's, local residents reported minor explosive activity, but since that time the volcano has been quiet.
Signal Colors and Their Meaning. The colors used in today's signals are green, yellow, red, lunar, and white (remember, we're talking about signals in North America). The color of a signal tells the engineer what he has to do, the location of that color, determines the speed at which he is allowed to do it.We will get to the speed thing in a minute.he colors used in today's signals are green, yellow, red, lunar, and white (remember, we're talking about signals in North America). The color of a signal tells the engineer what he has to do, the location of that color, determines the speed at which he is allowed to do it. We will get to the speed thing in a minute.
Red, green, and blue are the primary stimuli for human color perception and are the primary additive colors. The relationship between the colors can be seen in this illustration: The secondary colors of RGB, cyan, magenta, and yellow, are formed by the mixture of two of the primaries and the exclusion of the third. Red and green combine to make yellow, green and blue make cyan, blue and red make magenta. The combination of red, green, and blue in full intensity makes white. White light is created when all colors of the EM spectrum converge in full intensity. The importance of RGB as a color model is that it relates very closely to the way we perceive color with the r g b receptors in our retinas.