A tropical marine climate is usually experienced by islands and coastal areas 10° to 20° north or south of the equator. The ocean is the main influence in creating the tropical marine climate. There are two main seasons — the wet season and the dry season. The annual rainfall is 1000 to over 1500 mm. The temperature ranges from 25 °C to 35 °C. The trade winds blow all year round and are moist, as they have passed over warm seas.
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Wet season
The wet season of the tropical marine climate occurs during the period when the conditions of the atmosphere are not stable. At this time, the regions (10° to 20° north or south of the equator) experience tropical disturbances. Around this time islands like Trinidad and Tobago and Grenada are affected by the ITCZ (Intertropical Convergence Zone). Most rain falls between July and September.
Dry season
The dry season occurs when the conditions in the atmosphere are stable. During the dry season there is less rainfall than in the wet season. Around this time the tropical marine regions is influenced by anti cyclones. There is little difference between the wet season, from November to April, and dry season, from May to October.
Adaptations
The ecosystems of the tropical marine climate have to adapt to the dry season. Plants during the dry season must conserve water/moisture. However the extent of the adaptation depends much on the annual rainfall.
Hygrophytic ecosystems occur when there is a short dry period with a few rain showers. The soil in this ecosystem holds adequate water for plant growth. Most of the tropical marine ecosystems are close to true rain forests.
Mesophytic ecosystem
The mesophytic ecosystem is also known as a semi-evergreen forest. It is found where there is a long dry season that has little rainfall. There is less vegetation than in a rainforest and the layer structure is simpler. There are only two tree stories; trees shed their leaves or have very small leaves. This provides the plants a way to conserve moisture.
There are fewer epiphytes than a rain forest has as the canopy is dry. In the dry season the ground is covered by leaves that will not decay until the soil is moist. The trees often flower during the dry season and start to grow during the wet season. The soil is usually latasol.
Xerophytic ecosystem
The xerophytic ecosystem is also known as dry woodland. It is found in areas of rain shadow in the tropical marine climate. This ecosystem often develops soils that drain quickly.
The dry woodland is very different from the rainforest. The biomass is a lot less than a rainforest as there is little rain. The tallest of trees are only 15 to 25 meters high in the dry woodland. Dry woodland trees either have small leaves or shed their leaves. The trees have very thick bark and the trunks are crooked.
Variations
Mangroves grow in coastal wetlands, which are called hydrophytic ecosystems. The vegetation at the coast are usually adapted to sandy soil. The montane forests and elfin woodlands grow on the cool, moist, mountainous regions.