There are various phenomena that can reduce visibility, and you need to be able to recognise the descriptions and also be able to define each term. Some terms (like fog and mist) are very similar, so pay close attention to the blod elements below:
Haze: "A slight obscuration of the lower atmosphere, typically caused by fine suspended particles of a solid nature" Frontal fog: "Rain falling from relatively warm air aloft, evaporates into cooler air closer to the surface and causes it to become saturated" Fog: "The suspension of microscopic water droplets in the air reducing visibility at the earth's surface to less than 1000m" Mist: "The suspension of microscopic water droplets in the air reducing visibility at the earth's surface but to more than 1000m" Advection fog: "Microscopic water droplets formed when relatively warm, moist air moves over a cooler surface, and the temperature of the air is cooled to saturation by contact with the cold surface." Hill fog: "Low cloud covering high ground." Radiation fog: "Microscopic water droplets formed when the ground surface cools through the loss of energy, usually at night, cooling the air just above the ground to its saturation temperature." Steam fog: "Microscopic water droplets formed when evaporation takes place into cold air lying over warmer water."