There are four types of schemas are available in data warehouse. Out of which the star schema is mostly used in the data warehouse designs. The second mostly used data warehouse schema is snow flake schema.We will see about these schemas in detail.tar Schema: A star schema is the one in which a central fact table is sourrounded by denormalized dimensional tables. A star schema can be simple or complex. A simple star schema consists of one fact table where as a complex star schema have more than one fact table.
Sandstorms -- also called duststorms -- are caused by strong winds blowing over loose soil or sand, and picking up so much of that material that visibility is greatly reduced. The widespread abundance of loose sand in deserts makes them the most common locations for sandstorms to form.In desert regions at certain times of the year, sandstorms become more frequent because the strong heating of the air over the desert causes the lower atmosphere to become unstable.This instability mixes strong winds in the middle troposphere downward to the surface, producing stronger winds at the surface.he widespread abundance of loose sand in deserts makes them the most common locations for sandstorms to form. In desert regions at certain times of the year, sandstorms become more frequent because the strong heating of the air over the desert causes the lower atmosphere to become unstable.
Weathering causes the disintegration of rock near the surface of the earth. Plant and animal life, atmosphere and water are the major causes of weathering. Weathering breaks down and loosens the surface minerals of rock so they can be transported away by agents of erosion such as water, wind and ice. There are two types of weathering: mechanical and chemical. Mechanical Weathering. Mechanical weathering is the disintegration of rock into smaller and smaller fragments. Frost action is an effective form of mechanical weathering. When water trickles down into fractures and pores of rock, then freezes, its volume increases by almost 10 percent.