Through these experiments, you concluded that:

1. Three of the factors necessary for precipitation to occur include a difference in density between the warm and cold air masses, an upper atmosphere that has temperatures lower than the air in the rising warm air mass, and a significant amount of water vapor in the rising warm air mass. The temperature of the atmosphere decreases with the height of the atmosphere. When cold fronts form, air from the cold and warm air masses move as a result of a difference in densities. The more dense cold air pushes under the less dense warm air ahead of it. The air in the warm air mass rises. As the warm air rises, it encounters cooler temperatures and the rate of evaporation decreases. As the rate of evaporation becomes slower than the rate of condensation, any water vapor in the warmer air can condense and forms clouds and precipitation. When warm fronts form, air from the cold and warm air masses move as a result of their densities. The less dense warm air behind the colder air masses rises and slides over and above the cold air mass. As the warm air rises, it encounters cooler temperatures and the rate of evaporation decreases. As the rate of evaporation becomes slower than the rate of condensation, any water vapor in the warmer air can condense and form clouds and precipitation. The more water vapor the rising warm air mass contains, the more likely it is that there will be a greater amount of precipitation that occurs with both a warm and cold front.

2. In both cold and warm fronts, the rising of the warmer air mass is accompanied by a decrease in the atmospheric pressure. In a cold front, there is a decrease in pressure as the front forms because the cool air mass slides under the warmer air mass and pushes it upwards. The rising warm air results in a decrease in atmospheric pressure. This decrease is followed by an increase in pressure once the front has passed because of the cooler sinking air that moves in behind the warmer rising air. In a warm front, there is a decline in the atmospheric pressure as the front moves into an area because a warm air mass moves in behind a cooler air mass. As the warm air mass slides over the cooler air mass, there is a decrease in pressure. The pressure continues to drop as the front passes because of the warmer, rising air that moves in behind the cooler air mass.