TMJC 2025 JC1H2 C2 Lecture 1 Tropical Climate Classification

Higher 2 (9173) Tropical Environments TMJC C2 Lecture 1 Characteristics of Tropical Climates 2025 Page 1 of 8 LECTURE OBJECTIVES 1. Discuss the dynamism of natural environments in the tropics • Distinguish tropical climates based on the Koppen-Geiger climate classification system Introduction Climate is defined as the average weather conditions of a place over a long period of time, usually 30 years or more. It should not be confused with the weather, which is defined as the condition of the atmosphere at a particular time, or over a short period of time (hours or days). Most of the atmosphere, and therefore our climate and weather, is concentrated within the troposphere, within 16km of the Earth’s surface at the Equator and 8km at the Poles. (Don’t need to Memorise!) Before we begin: Recall the difference between the earth’s revolution and rotation. \

Page 2 of 8 (A) WHAT IS THE TROPICS? 1. The tropics is defined as a climatic region of radiation surplus 1 located between 30-35 degrees north and south of the equator (Fig. 1). a. Due to radiation surplus, areas within the tropics have high average annual temperatures of at least 18oC. There is however, some variation in the annual temperature range and diurnal temperature range within the tropics. b. Unlike temperature , precipitation patterns within the tropics differ widely , ranging from the: i. Humid tropics: Tropical Rainforest (Af) climate. ii. Seasonally Humid tropics: Tropical M onsoon (Am) climate and Tropical Savanna (Aw) climate. iii. Arid tropics: Sub-tropical steppe (BSh) climate and Tropical desert climate (BWh). Fig. 1: Areas defined as ‘tropics’ (B) WHAT ARE VARIOUS TYPES OF CLIMATES PRESENT IN THE TROPICS? 1. For the current A -Level Geography syllabus, we will examine 5 main types of climates present in the tropics, classified according to the Koppen -Geiger climate classification system. They are the: a) Tropical rainforest (Af) climate b) Tropical monsoon (Am) climate c) Tropical savanna (Aw) climate d) Sub-tropical steppe (BSh) climate & e) Tropical desert (BWh) climate 1 Radiation surplus means that the outgoing energy from the Earth (in the form of longwave terrestrial radiation) is smaller than the incoming energy from the sun (in the form of shortwave solar radiation) for the particular area.

Page 3 of 8 (C) WHAT ARE THE FEATURES OF THE TROPICAL RAINFOREST (Af) CLIMATE? 1. Temperature characteristics (Fig. 2): a. Mean annual temperature is high, usually between 26°C to 28°C. b. Seasonality of temperature is absent , with temperatures being constantly high throughout the year. c. Annual temperature range is small, usually less than 3°C. d. Diurnal temperature range is small at around 10°C, with average temperatures of 32°C in the day and 22°C at night. 2. Rainfall characteristics: a. Annual total rainfall is high, at more than 1500m