THE TROPICS

TROPICS 101 AND ANSWERS TO FAQs (March 2012)

 

Thanks to those of you who have responded with enthusiasm, or at least curiosity, to my email blasts about Costa Rica and the tropics.  Many of you, especially those who have never been to the tropics, wonder about the climate, rainforests, and many other things.  I am not ignoring your questions, and have compiled some information that helps explain some of these areas.

 

Those who are aware that Costa Rica is not an island but an isthmus often ask which ocean we live on.  Actually, we live in the mountains at 4000 feet elevation halfway in between the oceans, where the climate is ideal for our tastes.  (I hope the crack about the island doesn't sound snarky, but Costa Rica has a complex about being confused with Puerto Rico, which is in fact an island).

 

Costa Rica is in Central America, and is therefore part of North America, not South America.  It is also part of Latin America, which comprises nearly our whole hemisphere except US and Canada.  Although Costa Rica is part of fabled Central America, it is not at war and not particularly dangerous.  Costa Ricans are curious about the US, and do not resent us terribly.  They do believe that we possess enormous wealth, which in fact we do compared to them.  

 

The sun rises at about 6am and sets about 6pm every day with minor seasonal variation.

 

Summer, the drier of the two seasons, and sometimes ironically called the "dry" season, is roughly about December to April.  This is when most tourists visit to get away from northern winter.  The weather this summer (in Orosi Valley, which has its own microclimate) was absolutely delightful, with blue skies and high-seventies temps, during the first six weeks of my stay.  Rain has been more frequent the last few weeks and we hope the "dry" season is not over.  Note: even in the delightful weather I mentioned, the rain came occasionally, but late in the day and overnight.

 

Winter, the rainy, wet, or green season, occupies the rest of the year.  Having lived in semi-arid Southern California for so long, torrential rain was initially a novelty to me, but I can unequivocally say that I prefer summer.  But the green season is beautiful.

 

Earthquakes are much more frequent than in Southern California, as Costa Rica is at a confluence of many tectonic plates, and on the Pacific "Ring of Fire."

 

 

Arenal Volcano has been Costa Rica's biggest single tourist attraction, with thermal springs, hotels with hot pools and waterfalls, lava flow visable at night, loud rumblings, the full volcano experience but without the conflagration.  Recently, it has gone dormant or nearly so (sleeping).  We do have a couple of 11,000 foot volcanoes looking over our valley, one dormant and one fuming for the first time in 150 years (steam only, no lava or ash).  An eruption is not inconceivable, and I am told that when the dormant one blew in 1963, it covered the valley with half a foot of ash.

 

On the plus side, direct hit hurricanes are very unlikely here in Costa Rica, as can be seen on the map below of historical hurricane tracks.  We have experienced strong winds, peculiarly coming from the wrong direction, when the Caribbean and/or US are hit with hurricanes or tropical depressions.

 

We do not live in a rainforest, despite all of the rain we get.  Typically rainforests (think jungle) are at or near sea level.  We live on the edge of a cloud forest, also moist but different (cooler, higher, cloudier).  We do not have consistently high humidity as the beaches do.  The brisk clear air is sometimes compared to an eternal spring.

 

Costa Rica has many insects, but I do not wear deet or get bit unless I walk in the grass.  I have removed all grass from the area around our house and replaced it with crushed stone, for this reason and to minimize mud in the winter.  Ants are everywhere and require vigilance to keep them outside.  And you don't want to step on an anthill, some of which are enormous, in bare feet.  Biting insects are few in populated areas and you can enjoy the night air outdoors without fear.  You do not need to get malaria or other shots to visit here.

 

There are many interesting and colorful plants and animals here and a huge percentage of the land area is protected as national parks.  Tourism (including loosely defined eco-tourism) is the national biggest industry, followed by banana, coffee and pineapple exports.

 

Electricity is mostly generated by water power. A few days ago we heard an explosion, saw smoke at the hydro plant across the river and noticed the music stopped. Power, telephone and internet outages are common.  Our satellite TV originates from Mexico and is not hi-def.

 

As of today, regular gasoline costs have increased to $5.30 a gallon.  Premium is $5.43 and diesel is $4.84.  Prices are established by the government. Attendants pump your gas and add air to your tires.  The crude comes from Venezuela and is refined here by the government.  All cars are imported and new and used vehicles sell for more than double the American prices because of high import duties.  The government also owns the domestic breweries and distilleries, insurance companies, utilities, telecommunications, and other industries, but is opening some areas up to competition since ratifying CAFTA.

 

Costa Rica cuisine is unimaginative, consisting of rice, beans, fruits and vegetables.  Food served here does not resemble Mexican and is not spicy. Italian and other ethnic restaurants are numerous.

 

Almost all Costa Ricans participate in its universal health care system. Medical tourism is gaining in popularity because of high quality care at substantial  savings for cosmetic surgery and dental work.  I just got an implant and eight crowns.

 

Crime is said to be increasing, and police are more noticeable lately.  This is mostly petty crime, not violent.  Prostitution is legal in Costa Rica, but pimps and child sex tourism are not.  My observation, perhaps naive, is that recreational drug use in Costa Rica, which is illegal, is not extremely widespread.  However, as a point along the corridor from South America to Mexico and eventually the US, enormous quantities of cocaine pass through or are warehoused here and handed off from Colombian drug-runners to the Sinaloa cartel, with the attendant increase in violent crime, though not really affecting or visible to tourists. The US Navy, with whom Costa Rica willingly cooperates, has drug intercept missions in nearby waters.  US Homeland Security Secy Janet Napolitano was here a couple weeks ago to coordinate with La Presidenta Laura Chinchilla, who is open to considering legalization. 

 

It should be noted that Costa Rica has many laws and taxes, but enforcement is lax.

 

Most Costa Ricans do not speak much English, despite being bombarded by it on television, advertisements and products, except in tourist areas.  Spanish is the national language.  I have noticed the Ticos (as they are known) to be very light readers, but heavy texters and cell phone users.  Internet speeds are much slower than ours in the US, but we are all glad for what we have.

 

Costa Rica is a proud democracy with high voter participation, now attempting to match up its expenditures with tax revenue (what a concept, don't get me started).  Its relationship with the United States is very strong and the US Embassy here very large.  This is handy, because Costa Rica has no army, navy, or air force, only a coast guard.

 

This will be my last report for this trip.  Lin and I will be returning in late August.

 

For those wanting to read on, an illuminating if somewhat technical explanation of the tropics is presented as succinctly as possible in this excerpt from "TROPICAL NATURE: Life and Death in the Rain Forests of Central and South America" by Adrian Forsyth and Ken Miyata, 1985.  I have also attached graphics I have accumulated from elsewhere, including data with emphasis on Costa Rica charting hurricanes and earthquakes, in addition to subjects covered by their text:

 

"The Amazon forest is one of the wonders of our planet, and this vast expanse is the largest tract of rain forest in the world. But not all rain forests in tropical America are Amazonian, and although they may look insignificant on the map, the total area of these other rain forests is substantial. The most important of these non-Amazonian rain forests are those along the Caribbean coast of Central America, the northwest coast of South America, and southeastern Brazil.

Tropical rain forests are not accidents of nature, randomly placed on the earth's surface. There is an order to their distribution, and to understand this order we must consider how our planet hurtles through the universe.

 

The earth rotates about its axis once each day and travels around the sun once each year. This means that every point on the earth's surface receives the same amount of daylight each year, a total of 4,380 hours (give or take a few minutes, which we make up every so often in leap years). Our long summer days are precisely as long as our long winter nights and we finish the year in balance. This is true even in the polar regions, which have constant daylight during the summer and constant darkness during the winter. But the axis of the earth's daily rotation is not perpendicular to its orbit, and this inclination has several implications. It explains the familiar seasons of the temperate zones -- during the winter we are tilted away from the sun and during the summer we are tilted toward the sun. It also explains why the seasons are reversed in the southern hemisphere, because when the north is tilted toward the sun, the south is tilted away. What may be less obvious is that only part of the earth's surface ever receives direct overhead sunlight: those places that lie between two lines of latitude, the Tropic of Cancer in the north and the Tropic of Capricorn in the south. Within these borders, daylength remains more or less constant through the year. These are the tropics, or as Darwin was wont to call them, the intertropical regions.

The earth rotates about its axis once each day and travels around the sun once each year. This means that every point on the earth's surface receives the same amount of daylight each year, a total of 4,380 hours (give or take a few minutes, which we make up every so often in leap years). Our long summer days are precisely as long as our long winter nights and we finish the year in balance. This is true even in the polar regions, which have constant daylight during the summer and constant darkness during the winter. But the axis of the earth's daily rotation is not perpendicular to its orbit, and this inclination has several implications. It explains the familiar seasons of the temperate zones -- during the winter we are tilted away from the sun and during the summer we are tilted toward the sun. It also explains why the seasons are reversed in the southern hemisphere, because when the north is tilted toward the sun, the south is tilted away. What may be less obvious is that only part of the earth's surface ever receives direct overhead sunlight: those places that lie between two lines of latitude, the Tropic of Cancer in the north and the Tropic of Capricorn in the south. Within these borders, daylength remains more or less constant through the year. These are the tropics, or as Darwin was wont to call them, the intertropical regions.

The tropics are characterized by climatic features that residents of the temperate zones find unusual. There is little seasonal change in temperature, the type of seasonality we are accustomed to. Days and nights are about the same length throughout the year. In the tropics you don't have to worry about sending your children off to school on dark winter mornings, but you miss out on lingering, lazy summer evenings.

 

The intensity of tropical sunlight is difficult to describe, though the reason for its intensity is clear enough. It is related once again to the tilt of the earth. A beam of sunlight striking the earth in the temperate zones always strikes at an angle because the sun is never directly overhead. The radiant energy of this beam of sunlight is therefore spread out. In the tropics, the same beam of sunlight strikes the earth perpendicularly, or at least more directly than in the temperate zones, and the same amount of energy is therefore focused on a correspondingly smaller area. This effect is further intensified by the earth's protective mantle of air. Sunlight hitting the temperate zones at an angle passes through more energy-absorbing atmosphere than it does before striking the tropics. The intensity of tropical sunlight can be awesome. Newcomers must always be wary of its power, particularly if they are sporting pasty winter complexions; a shirt may not offer enough protection from the sun, and we have seen some visitors blister beneath thin coverings.

 

The intense tropical sunlight warms the air, and tropical latitudes are characterized by warm temperatures. Since daylength is more or less constant through the tropical year, there is relatively little fluctuation in temperatures through the year. Those of us who live in the temperate zones are accustomed to heatwaves during the summer and cold spells during the winter, both of which are consequences of varying daylengths. The long summer days heat the air, and if the air is stagnant, this heat accumulates and can't be lost during the short nights. The perpetual darkness in the Arctic region during the northern winters allows ample opportunity for air to lose its heat, and when this frigid air pushes into our more temperate latitudes it can cause devastating cold spells. But in the tropics the uniformity of daylength means that there are no such opportunities for heat to build up or be lost. Although there may be seasonal fluctuations in temperature, they tend to be minor.

 

The tropics are not necessarily characterized by high temperatures; if anything, they lack truly hot weather. The hottest place we have visited in tropical America was near Lake Maracaibo in Venezuela. We were searching for a mysterious little lizard, known from a single specimen collected in the early years of the century; but the heat made it difficult for us to work efficiently. The entire basin seemed suspended in still, hot air, and there were times when it seemed thick enough to eat. This was thornscrub rather than forest, and the scanty vegetation seemed to intensify the heat; yet as far as we recall, the temperature never reached 100 degrees Fahrenheit. This heat was exceptional apparently even for the region, and in general we rarely encounter temperatures over 90 degrees in our travels in the American tropics. When we lived in Arizona the summer temperatures were routinely over 100 degrees, occasionally exceeding 115 degrees, and summer heatwaves often bring temperatures over 90 degrees even in New England. So the lowland tropics we know are not extremely hot. But they are very warm, and they may seem even wanner because of the high humidity.

 

There is an exception to the rule of the warm tropics. As you climb a tropical mountain, the air temperature decreases at a predictable rate: for every 1,000 feet you climb, the temperature drops about 3 degrees Fahrenheit. When air rises it expands. Expanding air does work, and work requires energy. If the energy needed to expand comes from the air itself, heat is lost during the work and the air cools. Anyone who has felt the cold air coming from a deflating inner tube after a hot summertime float trip can attest to the cooling nature of expanding air. This cooling with elevation is typical of any mountainous region, but it seems particularly noticeable in the tropics, perhaps because it can be so unexpected and so refreshing. Whenever we wish respite from the uniform warmth of the tropical lowlands in Ecuador, all we have to do is find our way to Quito, the capital city perched 9,000 feet high in the Andes, where we can enjoy a climate as pleasant and invigorating as early fall in New England.

 

The difference in the intensity of sunlight on a tilted earth has other effects. It accounts for the major global patterns of air and water circulation, which in turn determine patterns of rainfall. Warm air is less dense than cool air, and when tropical air is warmed by the intense sunlight, it rises. As it rises, cooler air from the temperate latitudes takes its place, and the resulting flow of cool temperate air into the tropics has played a major role in both human and natural history. These steady winds, formed by the warming and rising of tropical air, are the trade winds, and as any sailor knows, trade winds move in predictable directions.

 

The direction in which they blow is another consequence of the earth's rotation. The surface of the earth moves faster at the equator than in the temperate latitudes. This may not seem right, but it is true. The earth is more or less spherical, and its greatest circumference is at the equator. Since the earth rotates around its axis once a day, a church steeple in Quito actually travels 24,000 miles in an easterly direction every day. In the temperate latitudes, the diameter of the earth is less: at the latitude of Minneapolis, for example, the earth is less than 17,000 miles in diameter, and a church steeple there moves some 300 miles per hour more slowly than its counterpart in Quito. If a mass of air moves from the equator northward, it should veer in an easterly direction because it is moving faster than the surface of the earth in that direction. Likewise, an air mass moving from the north to the equator veers in a westerly direction because it is moving more slowly than the surface of the earth and loses ground in a direction opposite the rotation. If the air moving to the equator should be cool air replacing the warm rising air, the winds that result come from a northeasterly direction. These steady trade winds also push ocean water, and when this water meets land, it must go somewhere. The northeasterly trade winds in the Caribbean push water against the Central and South American coast. As the water deflects northward, it moves in a northeasterly direction and is called the Gulf Stream. This tongue of warm water flows atop the cold temperate Atlantic Ocean.

 

Winds and ocean currents on a rotating, tilted earth help explain major patterns of rainfall. The trade winds pick up moisture as they flow across the ocean. Warm air can hold more moisture than cool air, and as northeasterly trades enter the American tropics, they pick up moisture from the sea. As the air warms further, it begins to rise, and rising air loses heat. When the air cools, its capacity for holding moisture drops, and the excess water falls as rain. The abundant rains produced by the cooling of moisture-laden tropical air give birth to the lush forests of tropical America—the piece of tropical nature we find so fascinating."

 

EARTHQUAKE MAPS