A climatogram, also known as a climograph, is a specialized graphical tool used to summarize the climate of a specific location. It provides a visual representation of long-term weather patterns, allowing for the comparison of different regions. This chart helps users quickly understand the general climatic conditions of an area.
The Two Essential Climate Measurements
The two measurements found on a climatogram are monthly average temperature and monthly average precipitation. These two factors are considered the most influential determinants of a region’s climate. Temperature regulates biological processes, while precipitation provides the necessary water for plant growth.
The data used are not measurements from a single year but represent long-term averages known as climatological normals. These normals are calculated from observations collected over a standard 30-year period, as recommended by the World Meteorological Organization (WMO). This 30-year average helps smooth out year-to-year weather variations, providing a stable reference point for climate analysis. The data points reflect the typical conditions for each of the 12 months.
Visualizing the Data: Dual Axes and Plot Types
The climatogram uses a single X-axis for the 12 months and employs dual Y-axes to display the two different types of data. Dual axes are necessary because the units of measurement for temperature and precipitation are entirely different and cannot share the same scale. The temperature scale is usually plotted on the right vertical axis, while the precipitation scale is on the left.
Temperature is represented by a smooth line graph connecting the 12 monthly data points. This line illustrates the annual thermal cycle, showing the warmest and coldest parts of the year. Precipitation is displayed using a bar graph, with each bar corresponding to the total average precipitation for that month.
Analyzing Climate Patterns
Once the data is plotted, the resulting graph becomes a tool for classifying and understanding a region’s environment. Analyzing the combined pattern of the temperature line and precipitation bars allows scientists to classify the area into a specific biome. For instance, consistently high temperatures and high precipitation suggest a tropical rainforest biome.
The shape and overlap of the two plots reveal the region’s distinct seasonal patterns. A large gap between the high temperature line and the low precipitation bars indicates a hot, dry season, such as in a desert or savanna. The combined information helps identify the growing season, which is the period when both temperature and moisture levels are suitable for plant life.