CLIMATE AND WEATHER

 

Climate is dynamic, not fixed. Climate is a synthesis of weather phenomena. It is the average weather conditions of a location for a period of over 35 years. Weather is the condition of the atmosphere at any given time and place. Climatology is the study of climate and attempts to discern similar weather statistics and identify climatic regions. The wide variety of climatic conditions can be grouped by general similarities into climatic regions.

 

Climates greatly influence ecosystems - the natural, self-regulating communities formed by plants and animals and their non-living environment. Climate determines the location of major ecosystems called BIOMES - forest, savanna, deserts, tundra and plant and soil combinations associated with them.

 

Weather elements that Combine to produce Earth’s Climates:

1)  Insolation (pattern of solar energy)

2)  Temperature (sensible heat energy content of the air),

3)  Precipitation (rain, sleet, snow, and hail; the supply of moisture),

4)  Air pressure (varying patterns of atmospheric density), and

5)  Air masses (regional-sized homogeneous units of air).

 

Climatic Classification:

 

Classification is the process of ordering or grouping data into related categories. A genetic classification is based on causative factors, such as the interaction of air masses. An empirical classification is one based on statistical data, such as data on temperature or precipitation.

 

1.  Climatic classification by Ancient Greeks

The ancient Greeks divided the world’s climates into three simple zones

a)   Torrid Zone: warmer areas south of the Mediterranean Sea

b)  Frigid Zone: areas near the poles to the North with very cold temperatures

c)   Temperate zone: the zone between the frigid and torrid zones which was considered the optimum climate.

2. Thornwaite’s Classification System:

C. W. Thornwaite adopted an empirical classification system to identify climatic regions using water balance criteria (moisture) in combination with vegetation types.

 

3. Köppen–Geiger Climatic Classification System

Designed by Wladimir Koppen (1846-1940) a German climatologist and botanist and his student Rudolph Geiger. They delineate climates according to:

1)  Average monthly temperatures and

2)  Total Annual Precipitation

 

Koppen’s climatic classification system does not consider:

a) winds, b) temperature extremes,

c) precipitation intensity, d) quantity of sunshine, e) cloud cover and f) net radiation.

 

Koppen’s Climatic designations:

 

The Koppen system uses upper case letters to designate climatic categories from the equator to the poles.

1.   A:  Tropical (equatorial regions)

2.   C:  Mesothermal - Mediterranean, humid subtropical, marine west coast regions

3.   D:  Microthermal (Humid continental, sub-arctic regions)

4.   E:  Polar (polar and arctic regions)

5.   H:  Highland climates.

6. B:  Dry (deserts and steppe climates)

 

The main climatic groups are divided into subgroups denoted by lowercase letters (a, f, b, w, c, d) that signify:

1)  average monthly temperatures,

2)  average monthly precipitation, and

3)  total annual precipitation

 

KOPPENS CLIMATIC CLASSIFICATION

 

A:  TROPICAL CLIMATES:

Consistently warm with all months averaging above 64.4^oF (18^oC). Annual precipitation exceeds water demand.

1. Af: Tropical rain forest climate (all months receive precipitation in excess of 2.4 inches.

2. Am: Tropical monsoon climate (a marked short dry season with one or more months receiving less than 2.4 inches)

3. Aw: Tropical Savanna climate (wet summer and dry winter).

 

B:  DRY - ARID & SEMI-ARID CLIMATES

Moisture demands exceed moisture supply

1. BW: deserts, 

a.    BWh: Hot low-latitude desert climate

b.   BWk: Cold mid-latitude desert climate

2. BS :  Steppe climate

c.    BSh  Hot low-latitude steppe climate

d.   BSk  Cold mid-latitude steppe climate

 

C:  MESOTHERMAL CLIMATES:

Warmest month above 50^oF (10^oC) and coldest month above 32^oF (0^oC) 

1. Cfa:  Humid subtropical without dry season, hot summers

2. Cwa & Cwb:  Humid subtropical winter dry

a – hot summer, warmest month above 71.6^oF (22^oC)

f – year round precipitation

w - winter drought, wet summers.

3. Cfb & Cfc:  Marine west coast, without dry season, warm to cool summers

f –  receives year round precipitation

b – warmest month below 71.6^oF (22^oC) with 4 months above 10^oC

c - 1-3 months temperature above 10^oC

4. Csa & Csb:  Mediterranean, summer dry

s – pronounced summer drought with 70% of precipitation in winter

a – hot summer with warmest month above 71.6^oF (22^oC)

b – mild summers, warmest month below 71.6^oF (22^oC)   

 

D:  MICROTHERMAL CLIMATES:

Warmest month above 50^oF (10^oC) and coldest month below 32^oF (0^oC). Snow climates

1. Dfa & Dwa:  humid continental, hot summers

a - hot summers, warmest month above 71.6^oF (22^oC)

f – year round precipitation

w – winter drought

2. Dfb & Dwb: Humid continental, warm summer

b – mild summer, warmest month below 71.6^oF (22^oC)

f – year-round precipitation

w – winter drought

3. Dfc, Dwc & Dwd: Subarctic, very cold winter

w – winter drought

f – year-round precipitation, without a dry season

c– 1-4 months temperature below 50^oF(10^oC

d – coldest month below -36.4^oF (-38^oC),

 

E:  POLAR CLIMATES

Warmest month below 50^oF (10^oC), ice climates

1.               ET:  Tundra climate (warmest month 32-50^oF, (0-10^oC)

2.               EF: Ice cap and sheets (warmest month below 32^oF (0^oC)

3.     EM:  Polar marine (all months above 20^oF (-7^oC).

 

H:  HIGHLAND (mountain) climates

 

GLOBAL WARMING 

Global Warming is the human-induced increase in the average global temperature near the earth's surface. Evidence indicates that we may be altering its atmosphere 10 to 100 times faster than the natural rate of change.

 

Greenhouse Gases:

The major Green house gases are: 

a)   Water Vapor (H²0),

b)  Carbon Dioxide (C0²),

c)   Ozone (0³),

d)  Methane (CH⁴),

e)   Nitrous Oxide (N²0),

f)     Chlorofluorocarbons (CFC's)

g)   Perfluorocarbons (PFC's) emitted from aluminum production has been discovered recently. 

 

Greenhouse effect:

 

First proposed by a Swedish Chemist, Svante Arrhenius in 1896. The green house effect refers to the situation where certain gases in the atmosphere trap heat in the troposphere and raise the average global temperature causing global warming.

 

1. Global temperature: Global average temperatures increased steadily from 1880 to 1940 and then fell slightly between 1940 and 1975. It has risen sharply since 1975. The IPCC estimates that the earth's surface mean temperature should rise 1 - 3.5⁰ C (1.8 - 6.3⁰ F) between 1990 and 2100

 

2. Global Sea-levels: Between 1900 and 1990, global sea levels has risen by 9-18 centimeters (3.5-7 inches).

 

POSSIBLE EFFECTS OF GLOBAL WARMING

 

Scientists also do not agree on the impacts of global warming but the suggested impacts include the ff.

1. Melting of Polar Ice Caps - raising sea levels all over the globe.

2. Rising sea levels could cause a shift in climates worldwide.

3. Shifts in climate would affect ecosystems, agriculture and housing needs.

4. Agriculture would be severely impacted.  Regions that produce much of the world's food could become unproductive. A warmer global climate could increase food production in some areas and lower it in other areas. 

5. Global warming could change the makeup and location of many of the world’s forests.

6. Global warming could also cause lakes, ponds and wetlands which have provided water for several urban dwellers, complex ecosystems and croplands) to dry up

7. Global warming would bring more heat waves and thus increase heat-related deaths among the elderly and people with heart diseases. 

8. Higher humidity levels would cause a rise in fungal skin diseases, yeast diseases and prickly heat and heat rash and also such insects as mosquitoes.