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Effects of Wind
Since granite is impervious to water, it does not expand and contract due to soaking up water. Instead, it expands and contracts once cracks open up on its surface, allowing water to seep in. One way in which these cracks are formed is through wind. Wind is formed due to thermal fluctuations in the atmosphere. Cold and hot winds weather granite by bombarding it with small grains of dust and dirt. It can also cause boulders to become unstable and fall, which can also create cracks. Once cracks are formed, the action of wind can further expand the cracks through the weathering process.
Effects of Rain
When rain falls, it collects in the cracks that opened up on the surface of granite. Rain water can be slightly acidic or basic, both of which can cause small reactions on the surface of the granite, which can break it down. When rain falls into cracks and crevices during the winter, it can become trapped and freeze. When rain freezes in the cracks, it expands the crack with it. Over time, this process can lead to cracks in the granite becoming larger and larger, breaking it down even further.
Effects of Heat
Large fluctuations in temperature can effect the weathering of granite. In desert environments, granite is subjected to large fluctuations between the heat of the day and the cold of the night. The heat of the day causes the rock to swell. With every 10-degree Celsius increase in temperature, there is a 2.5 times increase in the rate of a chemical reaction. When heat is coupled with water, like during a summer storm, the two factors can combine to create a stronger weathering process.
Effects of Cold
The cold causes granite to compress, or shrink, just as the heat causes it to expand. However, freezing temperatures also cause water to freeze and expand. During times of the year when rain is followed by a freeze, water trapped in cracks in the granite expand as the rock itself contracts. This causes the crack to expand and become weaker. When the weather warms, the water is heated as it melts, causing further chemical reactions to occur. The cycle of hot and cold, coupled with other meteorological factors such as rain and wind, is a part of the how granite is broken down into smaller pieces, eventually forming the rich soil in which plants thrive.