Understanding Global and Local Winds & Climatic Data

Global Wind Patterns

Permanent Winds: These winds blow consistently in the same direction throughout the year. Trade winds originate near 30 degrees latitude in both hemispheres, moving towards equatorial cyclones. As they pass over the seas, they gather moisture, leading to rainfall. Upon reaching these areas, the heated air rises, becoming antitrades that move in the opposite direction. Other permanent winds include the mid-latitude westerlies and polar winds.

Local Wind Systems

Local Winds: These winds blow in a specific region, typically in the same direction year-round. Examples include:

• Pampero winds: Cold and dry.
• Southeast winds: Cold and wet.
• Zonda winds: Warm and dry.

Climatograms: Analyzing Climate Data

A Climatogram is a double-entry graph summarizing precipitation, temperature, and weather data collected at a weather station. It displays the total monthly precipitation and the average monthly temperature. These averages are calculated over many years, typically 30 for significant climatic conclusions, 5 for short-term trends, or even a single year.

Understanding Climatogram Axes

Climatograms feature a horizontal axis representing the months of the year. The vertical axis on the left usually shows the temperature scale, while the vertical axis on the right indicates the level of rainfall. Ideally, the rainfall scale should be double the temperature scale to accurately represent dry seasons, based on the Gaussen aridity index:

Gaussen Aridity Index: Rainfall in mm = Temperature in °C x 2. If the rainfall in mm is less than twice the average temperature in °C, the month is considered dry.

Visualizing Climate Data

In a classic Climatogram, temperatures are represented by a line, and precipitation is shown in bars. Typically, the total annual rainfall and mean annual temperature are also included separately.