Rainfall in Guyana and the ITCZ

Warm, moist air, which is heated by solar radiation, rises vertically near the equator. As it rises, it cools and condenses, causing heavy rainfall. The rising air then travels north or south towards the poles and dry, cooler air descends near the tropics, before heading back towards the equator, in an atmospheric circulation pattern known as the Hadley Cell. The air which heads back along the surface of the earth towards the equator forms the trade winds. The trade winds blow mostly from the north-east in the northern hemisphere and from the south-east in the southern hemisphere and they converge near the equator in a zone called the ‘Inter-tropical-convergence zone’, or ITCZ for short. From space, the ITCZ appears as a band of thick and thunderous clouds which circle the earth around the equator.

The exact location of the ITCZ varies over time, but generally it oscillates north and south of the equator depending on the season. The ITCZ movement is generally greater over the land than over the sea. Over the land, the ITCZ moves north during May to July to around a latitude of 7 degrees North, and south during November to January, placing it well over the Amazon basin. The variation in the location of the ITCZ affects the wet and dry seasons of the tropics.

The oscillation of the ITCZ over the coast of Guyana causes the two wet-seasons experienced around June and December. Based on long-term rainfall records from 1892, average rainfall in Georgetown is about 2304 mm per year but can be as high as 3750 or as low as 1340 mm per year.

In the savannah region in north-eastern Brazil and southern Guyana however, the annual rainfall pattern exhibits a single wet season centered in June and a single dry season centered in December as a portion of the ITCZ over the land is mainly over Brazil at this time. Rainfall in the savannahs is significantly less with Lethem having about 1300 mm rainfall a year.

The ITCZ is the band of bright white clouds that cuts across the centre of the image.

The Iwokrama forest is located in the centre of Guyana just north of the savannah. It is therefore strategically placed to study the transition in climate between the two wet seasons found on the coast and rainforest areas and the one wet season found in the savannah. Iwokrama’s climate monitoring programme is doing just that.

Rain forests are rich in biodiversity and are home to many different plants and animals as well as indigenous communities. Humans, even those who don’t live in the rain forest, rely on it for resources such as building materials (wood and lianas), medicine and fruits.

Rain forests also provide essential environmental services for life on earth; they create soil as well as prevent soil erosion, produce oxygen though photosynthesis, maintain clean water systems, and are a key defence against climate change.  


The Hadley Circulation
Cell, the ITCZ and the
trade winds

The Iwokrama Rain Forest is 371,000 hectares, located in the heart of Guyana. Our mission is to develop strategies for conservation and sustainable development for local people in Guyana and the world at large. We are involved in timber, tourism and training.  Come and visit us in the rain forest or at http://www .iwokrama.org.

Iwokrama (black area) is located close
to the savannahs (pale area)
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Public financial management: 1966 – present (Final)

This is the fifth and final in a series of articles on the above aimed at highlighting the extent of our achievements in the post-Independence period.

LUCAS STOCK INDEXThe Lucas Stock Index (LSI) rose 0.54 per cent during the third period of trading in June 2016. The stocks of six companies were traded with 79,573 shares changing hands. There were three Climbers and one Tumbler. The stocks of Banks DIH (DIH) rose 1.98 per cent on the sale of 18,757 while the stocks of Demerara Distillers Limited (DDL) rose 5.26 per cent on the sale of 41,667 shares. In addition, the stocks of Demerara Tobacco Company (DTC) rose 1.51 per cent on the sale of 13,603 shares. In contrast, the stocks of Demerara Bank Limited (DBL) fell 5.26 per cent on the sale of 4,324 shares.  In the meanwhile, the stocks of Guyana Bank for Trade and Industry (BTI) and Republic Bank Limited (RBL) remained unchanged on the sale of 222 and 1,000 shares respectively.

Massy and Guyana (Part 1)

Steadfast Last year, this writer looked at the Massy Group of Companies formerly Neal and Massy to gain an understanding of the operations of this company which has been doing business in Guyana for the past 48 years. 


Value-added performance of the forest sub-sector: Erratic, weak, declining

Erratic Last week’s column highlighted what I consider to be a most distinctive feature of the extractive forest sub-sector’s performance in Guyana’s economy, during the past decade.

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The UK bids Europe farewell

On June 23 by a small majority, the British people voted to remove themselves from the European Union (EU). The decision has consequences for the Caribbean.

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What would life be without sport?

I wonder what it would be like to exclude sport completely from one’s life for, say, one year? No playing sport, no watching it, no reading it no discussing it no thinking about it even.

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Brexit: Lessons for Caricom

The results of the referendum held in Britain to determine whether or not it should remain in or leave the European Union (EU), has been won by voters who supported the leave option.

Director of Sport Christopher Jones and President of the Guyana Chess Federation Irshad Mohammed (centre) stand with some members of the 2016 Guyana Olympiad chess team. The team travels to Baku, Azerbaijan, for participation at the Olympiad in September. A signature qualifying tournament was not held to determine the members of Guyana’s Olympiad chess team.

Federation picks chess Olympiad team without holding qualifier

The Guyana Chess Federation (GCF) has decided upon a 2016 Guyana Olympiad chess team without hosting a qualification competition to determine the competence of its participants.

Quamina Farrier

Heavy on historic significance, Journey to Freedom failed as a musical

Several Guyanese plays of historic significance were recently staged at the Theatre Guild and National Cultural Centre as part of a Jubilee festival.


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