The most characteristic feature of energy prices is high volatility, which is the result of political and environmental factors. Many supply and demand factors also affect energy prices, especially global economic growth. When the economy is booming, energy demand increases; when the economy is depressed, energy consumption decreases. In addition to economic changes, severe weather conditions can also have a dramatic impact on energy, disrupting the supply of crude oil, gas or oil. Thus, such conditions can increase or decrease the need for customer associated with these energies. Also, in some of the world's largest natural gas fields, global energy prices are largely affected by political instability.