Base your answer to question 9 on the magazine article and diagram below.

Lake Effect Snow

During the cold months of the year the words “lake effect” are very much a part of the weather picture in many locations in New York State. Snow created by the lake effect may represent more than half the season’s snow fall in some areas.

In order for heavy lake-effect snow to develop, the temperature of water at the surface of the lake must be higher than the temperature of air flowing over the water. The higher the water temperature and lower the air temperature, the greater is the potential for lake-effect snow.

A lake-effect storm begins when air flowing across the lake is warmed as it comes in close contact with water. The warmed air rises and takes moisture along with it. This moisture, which is water vapor from the lake, is turned into clouds as it encounters much colder air above. When the clouds reach the shore of the lake, they deposit their snow on nearby land. A typical lake-effect storm is illustrated in the diagram below.

The area most likely to receive snow from a lake is called a “snowbelt”. Lake Ontario’s snowbelt includes the counties along the eastern and southeastern ends of the lake. Because the lake runs lengthwise from west to east, the prevailing westerly winds are able to gather the maximum amount of moisture as they flow across the entire length of the lake. There can be lake-effect snowfall anywhere around the lake, but heaviest and most frequent snowfalls occur near the eastern shore.

In parts of the snowbelt, the lake-effect combines with a phenomenon known as orographic lifting to produce some very heavy snowfalls. After cold air has streamed over the length of Lake Ontario, it moves inland and is forced to climb the slopes of the Tug Hill Plateau and the Adirondack Mountains, resulting in very heavy snowfall.

9. State why very heavy snowfall occurs in Tug Hill Plateau region?

Correct Answer:

Heavy snowfall occurs in Tug Hill Plateau due to increased condensation. Another significant reason for heavy snow fall is due to Orographic lifting.

Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. As the air mass gains altitude it expands and cools adiabatically. This cooler air cannot hold the moisture as well as warm air can, which effectively raises the relative humidity to 100%, creating clouds and frequent precipitation.