Visibility refers to how far you can see clearly. Good visibility means that you can see clearly for a long distance, which means there are few fine particles in the air and the air is fairly clean. Generally good visibility in clear weather and low humidity. Poor visibility indicates blurred or ambiguous vision. When fine particles in the air (rain, fog, dust, smog, etc.) fill the atmosphere, light is scattered and obscured, reducing visibility. Visibility affects traffic safety such as driving and aviation, so it is information that must be checked for safe and comfortable activities.