INVESTIGATING THE GLOBAL CLIMATE incredible range of weather conditions that affect the planet This diversity is reflected in the vari ous systems for classifying climates While regions can be identified in many different ways dividing the world into climatic zones based on similarities in temperature precipi tation and vegetation helps reveal patterns between otherwise disparate areas The clas sification scheme used in this book takes all of these factors into account and illustrates how for example southern California south ern Europe and the southern coasts of Africa and Australia separated by thousands of miles of land and ocean can all share a Mediterranean climate The impact of climate on the natural world and human life is wide ranging and var ies from region to region Generally however climate most directly affects vegetation and soils This in turn can influence settlement patterns and other human activities such as agriculture which is fundamental to our survival Technological responses to climate such as central heating air conditioning and irrigation have been developed as adapta tions to extreme temperatures or aridity Such adaptations are inadequate however to deal with the climatic phenomenon known
INTRODUCTION as global warming Althoughclimate describes long term weather conditions it should not be viewed as static or constant While Earth's overall climate has remained stable enough over the course of its history to sup port life it has gone through periods of great change tor example alternating between ice ages and periods of warmth Global warm ing is the name given to the rapid rise of air temperatures near Earth's surface over the past century which scientists have attributed to human causes Global warming threatens many of the planet s ecosystems and must be managed at an international level through innovative strategies and policies While weather is frequently a topic of con versation it is only part of a larger discussion Understanding climate and the long term effects of weather conditions provides a unique perspective on the development of both the geographical and cultural landscapes of the world And as long as global warm ing continues to endanger the environment understanding climate and its effect on the planet will continue to be of vital importance 9
CHAPTER 1 WHAT IS CLIMATE The aggregate long term weather or state of the atmosphere of any place is known as its climate For example a description of weather might be It rained yes terday in Phoenix while Phoenix gets only Io inches of rain per year would be a statement about climate Descriptions of climate include such weather elements as temperature precip itation humidity wind cloudiness and snow cover The study of climate is known as cli matology A variety of statistical measures and classification systems have been introduced over the years to help illuminate how climate impacts different regions across the world CLIMATE STATISTICs A location's climate can be described by vari ous statistical measures of the elements of weather and climate Mean or average val ues are usually computed for a fairly long time period such as 30 years These means are often calculated for each month and for the year as a whole Io
WHAT IS CLIMATE Extreme maximum and minimum figures help convey the degree of climate variabil ity Information on the frequency of various events such as the number of days per year with thunderstorms or the number of frosts in a typical winter is also important Temperature is one of the most important climate elements Daily mean temperatures may be computed as the average of the daily maximum and minimum temperatures or as the average of temperatures from all 24 hours These daily means can then be used to compute the mean value for a given month AVERAGE SEA LEVEL TEMPERATURES IN JANUARY BON 40 N 2O IN Over 80 50 to 80 20 to 50 10 to 20 Under 10 60's A COMPTIONS MAP A map of mean global surface temperatures for January shows the values adjusted to indicate what the temperatures would be if all the locations were at sea level To convert from degrees Fahrenheit to degrees Celsius subtract 32 and then divide by 1 8 II
