Defining Climate
Katie Muniz & Brian Bowen
Annual Averages and Variations
- Climatology- Is the study of Earth's climate and the factors that cause past, present, and future climatic changes.
- Climate describes the long term weather patterns of an area. These patterns include more than average weather conditions.
- Also describes annual variations of temperature, precipitation, wind, and other weather variables.
Normals
- Normals- the data used to describe an areas climate are compiled from meteorological records.
- These datas include daily high and low temperatures, amounts of rainfall, wind speed and direction, humidity, and air pressure.
- Data is averaged on a monthly or annual basis for a period of at least 30 years to determine the norm.
Limitations of normals
- While normals offer valuable information, they must be used with caution. Weather conditions of any given day might differ widely from the norm.
- While climate describes the average weather conditions for a region, norms apply only to the specific place where the meteorological data were collected.
Causes of Climate
- From watching the weather reports the climates around the country vary greatly. For example, on average, daily temperatures are much warmer in Dallas, TX, than in Minneapolis, MN.
- There are several reasons for such climate variations, including difference in latitude, topography, closeness of lakes and oceans, availability of moisture, global wind patterns, ocean currents, and air masses.
Latitude
- Tropics- The area between 23.5 degrees South and 23.5 degrees North of the equator.
- Temperate Zones- lies between 23.5 degrees and 66.5 degrees North and South of the equator.
- Polar Zones- Located from 66.5 degrees North and South of the equator to the poles.
- The amount of solar radiation received by any one place varies because Earth is tilted on its axis, this affects how the sun's ray strike our surface.
Topographic Effects
- Water heats up and cools down more slowly than land. Large bodies of water affect the climate of coastal areas.
- Temperatures in the lower atmosphere generally decrease with altitude, mountain climates are usually cooler than those at sea level.
Air Masses
- Two of the main causes of weather are the movement and interaction of air masses, air masses also affect climate.
- Average weather conditions in and near regions of air mass formation are similar to those exhibited by the air masses themselves, for example consider the Island of Dominica.