Weather Patterns

To branch off of Mount Roraima's hydrologic cycle, Mount Roraima has an extremely unique and quickly changing weather pattern due to two factors: its 1) mass and 2) surroundings. I will be primarily focusing on the impact of the tepui's surroundings which create its fickle weather.

The mountain is so massive that it creates its own weather

The climate in this region is constantly hot and humid. The average temperature is 97 degrees Fahrenheit (36 degrees Celsius), but thanks to the Environmental Lapse Rate, the temperature drops dramatically due to the high altitude and falls around 50 degrees Fahrenheit (10 degrees Celsius) at the top of the mountain, night or day. Also once at the top, it is windy and more often than not, raining. (Since there is such extreme wind and rain at the "peak" of the tepui, this is the most acclaimed reason why the top does not complete itself and is in the form of a plateau).

The rain, which varies between 1500 and 1750mm annually, is usually accompanied by thunderstorms. Even in the dry season (a mere three months out of the year), the weather being clear at the top of the tepui is very seldom, hence why this landform is known as one of the wettest places on Earth. There is a saying about Mount Roraima's weather pattern: "If you can see the mountain, it is going to rain. If you can't see the mountain, it is already raining!" 

In the middle of a rainfall, wrapped in dense fog at the top of Mount Roraima

This peculiar weather pattern, though odd, is a daily occurrence for Mount Roraima due to its surroundings. Since the landform is guarded by such a thick rainforest, the extreme tropical heat causes the moisture and humidity in the rainforest to rise, then condense over the mountain. And, since warm air can hold more water vapor, the condensed moisture turns into heavy rain clouds. This process is known as convection. The rain then creates long morning and afternoon thunderstorms, often resulting in flash flooding. 

A typical view of Mount Roraima in the morning hours

The calm after the storm at the summit of Mount Roraima, showing some radiation fogging

Helpful hint to hikers: the best season to climb this ever-popular spot is between July and January. Although it will still be extremely wet, 50% of the annual rain Mount Roraima receives is between April through September, so it is important to dodge the rainy season. Also, it is against national park policies to leave after 2 p.m., again, due to large chance of rain. 



http://dinets.info/roraima.htm
http://www.summitpost.org/monte-roraima/151790
http://www.tourismontheedge.com/best-of/mount-roraima-a-mystified-hiking-experience.html
http://www.vacationideas.me/south-america/mount-roraima-guyana-venezuela-brazil/
http://www.biosferabrasil.com/download/guide%20-%20Roraima.pdf