Ch. 14 - Climate Climatology – the study of Earth’s climate and the factors that affect past, present, and future climatic changes. Climate is the long-term weather patterns of an area. Includes annual variations of temperature, precipitation, wind, other weather variables, and average weather conditions. An area’s climate is compiled from meteorological records, which are continuously gathered at thousands of locations around the world. This includes daily high and low temperatures, amounts of rainfall, wind speed and direction, humidity, and air pressure. The data is averaged on a monthly or annual basis for a period of at least 30 years to determine the normals for a location. Normals are not intended to describe usual weather conditions. They are simply the average values over a long period of time.

Climate Zones 1. Tropics – the area between 23.5° south of the equator and 23.5° north of the equator. Receives the most solar radiation. 2. Temperate – lies between 23.5° & 66.5° north and south of the equator. 3. Polar – located from 66.5° north and south of the equator to the poles.

Climate Classification Koeppen classification system – it’s based on average monthly values of temperature and precipitation. 1. Tropical Climates 2. Dry Climates 3. Mild Climates 4. Continental Climates 5. Polar Climates Fig. 14-4 (pg. 365)

Heat Islands – the climates is warmer than in surrounding areas. Microclimate – a localized climate that differs from the main regional climate. Heat Islands – the climates is warmer than in surrounding areas. Concrete buildings, asphalt, etc. reflects more solar radiation and causes urban areas to warm up more than rural areas.

Climatic Changes Ice Ages – periods of extensive glacial coverage in which the average global temperatures decreased by 5° C. They alternate with warm periods of interglacial intervals (we’re in this now). The intervals are approximately 10,000 years. Short-term climatic changes are seasons. Why do we have seasons? El Nino is another example of short-term climatic changes. Warm ocean currents develop off the western coast of South America.

El Nino trends causes the jet stream to dip farther south, bringing violent storms to California and the Gulf Coast, which are usually south of the storm tracks. The effects of hot, moist upper air spread farther east, bringing stormy weather to areas that are normally dry and drought conditions areas that are normally wet.

The Earth’s axis and orbit may trigger climatic changes. Maunder minimum – a period of very low sunspot activity (11 year cycles). The low activity causes unusually cold climatic episodes called “Little Ice Age”. The Earth’s axis and orbit may trigger climatic changes. The Earth’s elliptical orbit appears to change, becoming more elliptical, then more circular, over the course of a 100,000 – year cycle. Fig. 14-14. The current tilt of the Earth is 23.5°. The angle of the tilt varies from 22.1° to 24.5° every 41, 000 years. Earth’s wobble occurs as it spins on its axis. This occurs over a period of about 26,000 years.

The Human Factor Greenhouse effect – the retention of heat by the atmosphere due to certain greenhouse gases (carbon dioxide), that aids in this. Radiation travels in short wavelengths; as it enters the atmosphere it loses a little energy. When it hits the Earth’s surface it loses more energy as it reflects back. The radiation is now in long waves with less energy; the radiation can’t escape the atmosphere. This causes the atmosphere to heat up some. Global warming – the rise in global temperatures due to greenhouse gases trapping more solar radiation. The warmest years on record have occurred in the last 2 decades. This could cause melting of ice caps, flooding may occur because of this, deserts could spread, and more severe storms may arise. Scientists haven’t agreed on what’s causing global warming. Most feel the evidence shows the large levels of carbon dioxide. What’s causing the increase? Can anything be done to stop it?

Any process of burning fossil fuels gives rise to the increase in carbon dioxide levels. Mainly car exhaust. Some easy ways to conserve energy includes turning off appliances and lights when a room is not in use, turning down thermostats in the winter, and recycling.