When we talk about climate we are referring to weather at a given place over a long period of time. The general measurements of climate are the average yearly temperature and the average yearly rainfall, and the seasonal cycle.
There are differences in the climate between towns and surrounding country sides. Urban areas are warmer than rural areas because all the buildings soak up heat and retain it. Heat is also being given off by central heating and by people. There is more sunshine in rural areas than in towns because of the pollutants in the atmosphere.
Local climatic patterns are called microclimates. Microclimate is the study of local weather of a small area. Plants create microclimatic differences, primarily by their use of water and their effect on winds. In farm areas, wind breakers are gown to make favorable microclimates.
Latitude: The physical conditions that affect climate are latitude, prevailing winds, ocean currents, nearness to the sea, altitude, and mountains. The affect latitude has on weather is the way that the earth is heated by the sun. Temperature varies with distances from the equator. The distance from the equator is measured in degrees of latitude, which are the lines across a map. The equator is 0° around the equator, and there is no winter season.
The North Pole is 90° north latitude and the South Pole is 90° south latitude, and the sun’s rays strike at a slant and are without direct sun for half the year. In the temperature zone, 30° to 60° latitudes north and south are the middle latitudes. Here summer temperatures can equal that in the tropics and winter temperatures are almost equal to that near the poles.
Prevailing winds: The United States major air flow is from slightly southwest to slightly northwest. The air flows in this manner because of the repeated invasion of cold air from the polar front coupled with the complications caused by air that is forced over mountains that the weather of the United States is unstable. Violent weather changes are caused by polar fronts and other factors. Most of North Americans live in the belt of “Prevailing Westerlies Winds”. Prevailing Westerlies are air masses often from west to east.
Ocean Currents: Bodies of water do not heat up as quickly as bodies of land. Over the period of summer, bodies of water become warmer and warmer. Bodies of water maintain their heat longer than bodies of land. In the winter the ocean is warmer than the land.
Ocean currents are caused by convecting currents in the ocean. The unequal heating of the ocean causes the currents to rise. The winds push the surface currents along. As ocean currents move they warm or cool the air above them and consequently the warm or cold currents near land can affect the climate. Areas where the wind blow from the ocean toward land have more annual rainfall than area where the winds blow toward the water.
Nearness to sea: Nearness to the sea has a part to play in the climate because air masses change with seasons and warm or cool ocean currents off shore.
Altitude: Altitude is distance above sea level. Consequently altitude affects air pressure. The higher you ascend above sea level the air gets thinner or less dense and the air pressure also decreases with increasing elevations.
Mountains: A contributing factor that determines the weather or climate, are the mountains. When air masses collide with high mountains they may either rise above the mountains or turn aside.