Earth Science: THE CLIMATE SYSTEM
Earth is home to a number of different climate zones, influenced by various factors. A commonly used system of categorization identifies zones based on their average temperatures, dividing the world into polar, temperate, subtropical, and tropical zones.
Discovery The Earth – The Global Climate
Different climates exist on various parts of Earth, from the dry heats of deserts to the freezing winds of polar ice caps. All of these climates can be taken together to calculate the average global climate.
Climate is the full range of weather conditions experienced in a particular place over several decades or longer, including daily and seasonal changes. Weather, however, refers to short-term conditions during time periods ranging from as little as a few hours to a length of a couple of weeks-or, at the most, a particular season.
What determines climate?
Many conditions and processes work together to determine the climate of a particular area. Primary climatic factors include a region’s latitude, its elevation, and the features of its terrain, as well as the amount of solar radiation it receives. From these primary factors arise secondary climatic factors, such as ocean currents, wind systems, and other natural cycles.
Climate observations
Depending on the size of the area under consideration, climate can be divided into microclimate (sometimes areas only a few yards or meters in size), mesoclimate (extending over several hundred miles), and macroclimate (encompassing entire continents or even Earth as a whole). Climate arises from the interaction of Earth’s five “spheres”: the atmosphere (air), the biosphere (living things), the pedosphere (soil), the lithosphere (rocks and minerals), and the hydrosphere or cryosphere (water, including ice). Together, these form the geosphere.
A multitude of climatic factors influence each of the spheres, producing the geosphere’s overall climate. In order to describe weather and climate in the atmosphere, scientists collect data about the various climatic elements, such as temperature, air pressure, humidity, wind speed, and direction.
After data has been collected over a long period of time, average values can be calculated. When scientists compare these with current data, they can make predictions about long-term patterns in the climate.
NORTH ATLANTIC OSCILLATION (NAO)
The NAO index describes the difference between pressure systems over the Atlantic; a large pressure difference is a positive index while a small is a negative index The index fluctuates, influencing Northern Hemisphere weather.
It is not yet known whether the positive index over recent decades is related to unusual climate change.