WednesdayMay 11, 2011

(El Nino and La Nina; Koppen Climates)

The Launch PadWednesday, 5/11/11

What is being

illustrated in this picture?

AnnouncementsPlease check your yearly

average in this class.If you are below 70 for the year, please come and see

me ASAP!There are only two more

grades remaining!

Assignments For This Six-Weeks Date Issued Date DueLab – Air Masses, the Mid-Latitude

Cyclones, and Weather Maps 4/20 4/25

Lab Quiz - Air Masses, the Middle-Latitude Cyclone, and Weather Maps 5/3 5/3

Lab – Weather Maps 5/4 5/6

Lab - National Weather Service Southern Regional Headquarters Local Weather

Information5/6 5/6

Test 10 5/10 5/10

El NiñoEl Niño is a warm

countercurrent that flows southward along the coasts of Ecuador and Peru, usually

during the Christmas season.

This warm current blocks the upwelling of colder,

nutrient-filled water, and anchovies starve from lack

of food. The strongest El Niño events on record occurred between

1982–83 and 1997–98.

El NiñoThe 1997–98 El Niño event caused

heavy rains in Ecuador and Peru and ferocious storms in California.

El Niño is related to large-scale atmospheric circulation.

The pressure change between the eastern and western Pacific is

called the Southern Oscillation.

Changes in trade winds creates a major change in the equatorial

current system, with warm water flowing eastward.

El Nino effects are highly variable depending in part on the

temperatures and size of the warm water pools.

Normal Conditions

Figure 18.23 A

El Niño

La Niña La Niña events are the opposite of El Niño.

La Niña is triggered by colder-than-average surface temperatures in the eastern

Pacific. A typical La Niña winter

blows colder than normal air over the Pacific Northwest and northern Great Plains, while warming much of the

rest of the United States.Greater precipitation is

expected in the Northwest during a La Niña year.

El Niño and La Niña Events associated with El Niño and La Niña are now

understood to have a significant influence on the state of weather and climate almost everywhere.

World Climates and Global Climate Change

The Climate System

Climate is an aggregate of weather.

Climate involves the exchanges of energy and

moisture that occur among the:

atmosphere,hydrosphere,lithosphere,

biosphere, andcryosphere (ice and snow)

Several components of Earth’s climate

system.

World Climates

All locations on Earth have a

distinctive climate.The most important

elements in a climatic

description are:temperature,

and precipitation.

Climate Classification A climate classification system

brings order to large quantities of information, and

many climatic-classification systems have been devised.

The Köppen classification of climates is the best known

and most widely used system.

This system uses mean monthly and annual values of

temperature and precipitation.

Climate Classification

The Köppen classification of climates describes five principal

climate groups:humid tropical (A)

dry (B)humid middle-latitude with mild

winters (C) humid middle-latitude with severe

winters (D)polar (E)

A, C, D, and E climates are defined on the basis of temperature

characteristics.Precipitation is the primary criterion

for the B group.

Climates of the World Based on the Köppen Classification

Figure 20.4

Köppen Climates Humid Tropical (A) Climates

These are winterless climates, with all months having a mean

temperature above 64ºF.The two main types are:

wet tropics, with high temperatures and year-round rainfall, luxuriant vegetation

(tropical rain forest.)These climates exist in a

discontinuous belt astride the equator, and are strongly

influenced by the equatorial low pressures.

Köppen Climates Humid Tropical (A) Climates

These are winterless climates, with all months having a mean

temperature above 64ºF.The two main types are:

tropical wet and dry, which are found poleward of wet tropics and

equatorward of the tropical deserts.

These climates consist of tropical grassland (savanna), with seasonal

rainfall.

Comparison of A-Type Climates

Figure 20.6