Trewartha’s climate classification scheme, developed by American geographer Glenn Thomas Trewartha in 1966, is another method used to classify climates based on temperature and precipitation patterns. This system builds upon the earlier work of Köppen and Thornthwaite but incorporates additional factors to provide a more detailed classification of global climates. Trewartha’s scheme considers not only temperature and precipitation but also factors such as the distribution of precipitation throughout the year, humidity, and seasonality.
Components of Trewartha’s Scheme
Trewartha’s climate classification system uses the following criteria to classify climates:
- Temperature Regime:
- Trewartha distinguishes between different temperature regimes, considering both annual and seasonal variations in temperature.
- Precipitation Regime:
- This includes the amount of precipitation, its distribution throughout the year (seasonality), and the number of dry months.
- Humidity and Moisture Availability:
- Trewartha considers humidity levels and moisture availability, which influence vegetation types and agricultural practices.
Classification of Climates
Trewartha classified climates into several types based on these criteria:
- Tropical Moist Climates (Group A):
- Tropical Rainforest (Af): High temperatures year-round with abundant rainfall throughout the year. Example: Amazon Rainforest.
- Tropical Monsoon (Am): Similar to Af but with distinct wet and dry seasons. Example: Mumbai, India.
- Dry Climates (Group B):
- Semi-arid (BS): Regions with moderate rainfall and a pronounced dry season. Example: Steppe regions of Central Asia.
- Arid (BW): Very low rainfall throughout the year. Example: Sahara Desert.
- Temperate Climates (Group C):
- Mediterranean (Cs): Hot, dry summers and mild, wet winters. Example: Southern California, USA.
- Humid Subtropical (Cfa): Hot, humid summers and mild winters with moderate rainfall. Example: Southeastern United States.
- Continental Climates (Group D):
- Warm Continental (Dfa): Hot summers and cold winters with moderate precipitation. Example: Chicago, USA.
- Cold Continental (Dfc): Cold winters and mild summers with moderate precipitation. Example: Moscow, Russia.
- Polar Climates (Group E):
- Tundra (ET): Cold winters and cool summers with low precipitation. Example: Northern Canada.
- Ice Cap (EF): Extremely cold temperatures year-round with very low precipitation. Example: Antarctica.
Example Application: Mediterranean Climate
Let’s apply Trewartha’s scheme to understand the Mediterranean climate:
- Characteristics: Mediterranean climates have hot, dry summers and mild, wet winters. Trewartha’s classification (Cs) reflects the seasonal variability in precipitation and temperature.
- Example Region: Southern California, USA
- Temperature Regime: Hot summers and mild winters.
- Precipitation Regime: Moderate rainfall in winter and very dry summers.
- Humidity: Moderate to low humidity levels during the dry season.
Comparison with Other Classification Systems
Trewartha’s scheme provides a more detailed classification compared to Köppen’s system, especially in distinguishing between different types of temperate and continental climates based on seasonal variations in temperature and precipitation. It also considers humidity levels, which are crucial for understanding the overall climate comfort and vegetation patterns.
Conclusion
Trewartha’s climate classification scheme offers a comprehensive framework for understanding global climate patterns based on temperature, precipitation, humidity, and seasonal variability. It provides valuable insights into how climate influences ecosystems, agriculture, and human activities across different regions of the world. By considering a broader range of climatic factors, Trewartha’s scheme enhances our understanding of the complex interactions between climate dynamics and environmental processes.
