Climate isn't the same thing as weather. Weather is the condition of the atmosphere over a short period of time; the climate is the average course of weather conditions for a particular location over a period of many years. One of the factors that influence climate is the angle of the sun's rays. In the tropics, between 23.5° N and 23.5° S, there is at least one time of year when the noontime sun is directly overhead and its rays hit at a direct angle. This produces a hot climate with relatively small temperature differences between summer and winter. In the Arctic and Antarctic (north or south of 66.5° latitude), there are times of year when the sun is above the horizon 24 hours a day (a phenomenon known as midnight sun) and times when it never rises. Even in the summer, the sun is low enough for temperatures to be lower than in the tropics, but the seasonal changes are much greater than in equatorial regions. Interior Alaska has seen temperatures as high as 100 degrees Fahrenheit (38 degrees Celsius). Closer to the Equator lie the temperate regions. These include the United States, Europe, China, and parts of Australia, South America, and southern Africa. They have the typical four seasons: winter, spring, summer, and fall. This information can be published in our peer reviewed journal with impact factors and are calculated using citations not only from research articles but also review articles (which tend to receive more citations), editorials, letters, meeting abstracts, short communications, and case reports. The inclusion of these publications provides the opportunity for editors and publishers to manipulate the ratio used to calculate the impact factor and try to increase their number rapidly. Impact factor plays a major role for the particular journal. Journal with higher impact factor is considered to be more important than other ones.