Bad weather is of considerable economic significance. The construction industry (road building), manufacturing industry (sensitive processes and commodities), power industry (electricity and gas supply) are much affected by relatively minor weather changes. Road and rail communications are vulnerable to cold weather and particularly to snow. Accidents increase in bad weather. Bad weather, by keeping people at home, can cause a fall in retail sales. It has been estimated that savings resulting from response to weather reports was of the order of $1,000 million per year in the USA. Bad weather has a major impact upon agricultural activities, both during the plant growth phases and during crop storage.
Bad weather plays a factor in the physical and emotional health of people. Hot dry winds may be, in part, responsible for increases in respiratory, cardio-vascular problems, road accidents and crimes. Approaching high pressure systems apparently trigger increased blood pressure, fatigue and edginess which when combined can cause road accidents. The approach of a warm, humid front and a swift drop in temperature or atmospheric pressure can bring on a coronary. Winds in conjunction with pollution increase respiratory problems. A rise in temperature above the normal seasonal average (not just high temperatures) is responsible for cases of assault and rape during summer heat waves. Theft increases during the winter.
Weather is the day-to-day variation of climatic and atmospheric conditions at any one place, or the state of these conditions at a particular place at any one time. Such conditions include humidity, precipitation (rainfall), temperature, cloud cover, visibility and wind. Climate is the sum of weather conditions at a particular place over time. It encompasses all the meteorological elements (scientific observations of the atmosphere) and the factors that influence them, the most important of which are: the effect of latitude and the tilt of the earth's axis to the plane of its orbit around the sun; the movement of different wind belts over the earth's surface; the temperature difference between land and sea; contours of the ground; and location of the area in relation to ocean currents.
The regions of the world with the most variable climates are located near the tropics, namely those countries with less developed economies and seemingly less able to mobilize resources to compensate for the impact of adverse weather conditions.