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Geography 1001:

Climate & Vegetation

Instructor: Andrés Holz

Agenda for Lecture 11: T Oct 2nd

• Logistics

– 1st Exam in 9 days!

– Take advantage of my office

hours

– Students with documented

excuses, please email me

this week

• Review Lecture 10

• Lecture 11

Review Lecture 9

Water Resources:

• The Hydrologic Cycle

• Our Water Supply

–Water in the West

Hydrologic Cycle Model

Figure 9.1

Water Withdrawal by Sector

Figure 9.21

Global Water Scarcity

Figure 9.22

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Total water use (2000)

Figure 9.11

Total water use (2000)Drought throughout this last summer

• http://www.drought.unl.edu/dm/12_week.gif

Chapter 10:

Global Climate Systems

• Climate components & relationships

• Köppen Climate Classification

– Criteria

– Benefits & Drawbacks

• Köppen-Geiger Climate System

– Earth’s Climate Classification

Climate

• Climate is weather over time & space (i.e.

> 30 days)

• Climatology is the study of climate

• Climatic regions are areas with similar

weather statistics

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Climate Components (5)

• Insolation

• Temperature

• Pressure

• Air Masses

• Precipitation

Climate Components: Insolation,

Latitude, and daily & seasonal variations

Climate Components: Temperature,

latitude

altitude Land/water heating

differences

Cloud cover

Climate Components: Pressure,

Variation in pressure���� winds patterns (spatial & temporal) ���� differences in Temps

Climate Components: Air Masses,

Spatial/ temporal patterns

Climate Components: Precipitation

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Precipitation in North America

Figure 9.6

Seasonal Pressure and Precipitation Patterns

Climate Relationships

Figure 10.3

Generalized Climate Regions

Figure 10.4

Köppen Climate Classification

• Empirical (data) system

• Began with heat zones in 1884

• Published first wall map in 1928

Köppen Classification:

hierarchical criteria

1. Average monthly temperatures

2. Average monthly precipitation

3. Total annual precipitation

Do you think that boundaries of this classification are “perfect”?

There are not perfect. Think of the scale…the whole planet!….

Thus, the trend is more important than the exact location of the

boundaries.

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Köppen Classification: benefits &

drawbacks

• Benefits of this classification

– It correlates reasonably with actual world

– Standard worldwide and readily available data

• Drawbacks (doesn’t include)

– Winds, temps extremes, precipitation

intensity, amount of sunshine, cloud cover, or

net radiation

– The causes of precipitation or temperature

patterns

Köppen-Geiger Climate System

Figure 10.5

Classification Categories (based

purely on temperature criteria)

• (A) Tropical – equatorial and tropical

latitudes

• (C) Mesothermal – mid-latitudes, mild

winters

• (D) Microthermal – mid- and high-

latitudes, cold winters

Classification Categories (based

purely on temperature criteria)

• (E) Polar – high latitudes and polar regions

• (H) Highland – compares to lowlands at

the same latitude, highlands have lower

temperatures

• (B) Desert – permanent moisture deficits*

Köppen-Geiger Climate System

Figure 10.5

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Sub-climates

• Within each climates, the subtypes are

based on precipitation gradients

Tropical Climates (A)

• Consistent day length and insolation input

produce consistently warm temperatures

• Inter Tropical Convergence Zone (ITZC)

brings rain as it shifts seasonally with the

high sun

• Warm ocean temperatures and unstable

maritime air masses

Tropical Climates

• Equatorial and tropical latitudes

– Tropical Rain Forest Climates – rainy all

year

– Tropical Monsoon Climates – 6 to 12

months rainy

– Tropical Savanna Climates – less than 6

months rainy

Precipitation

Gradient

Tropical Climates (A)

~36% of the earth’s

surface—the most

extensive climate

category.

Tropical Rain Forest

Figure 10.7

Tropical Monsoon

Figure 10.8

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Tropical Savanna

Figure 10.9

Mesothermal Climates C

• Shifting air masses of maritime and

continental origin

• Migrating cyclonic and anti-cyclonic

systems bring changeable weather

conditions and air mass conflicts

• Summers transition from hot to warm as

you move away from tropics

Mesothermal Climates

• Midlatitudes, mild winters

– Humid Subtropical – hot-summer

climates

– Marine West Coast – warm to

cool summers

– Mediterranean – dry-summer

climates

Precipitation

Gradient

(seasonality)

Mesothermal Climates (C)

• 2nd largest % of earth’s surface (land-

ocean) ~27%.

• Area alone is considered� only fourth.

• Together, A & C climate dominate more

than half of earth oceans and about one

third of the land area.

• ~ 55% of people around the world lives in

C’s climates� Meso-thermal� middle-

heat, or middle temps

Mesothermal Climates (C)

Figure 10.11

Mesothermal – Humid Subtropical

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Mesothermal – Marine West coast

Figure 10.16

Mesothermal – Mediterranean

Microthermal Climates D

• Mid and high latitudes, cold winters

– Humid Continental – hot to warm

summers

– Subarctic – cool summers

Average

Annual

Temperature

Gradient

•Increasing seasonality (daylenght and

Sun altitude)

• Humid microthermal�long winters & some summer warmth.

• ~ 21% of earth’s land surface is influenced by these climates = about 7% of earth’s total surface.

• These climate experience great temperature ranges, related to continentality and air mass conflicts.

• Given the lack of land mass in the S-hemisphere, this climate can only be found in the N-Hemisphere.

Microthermal Climates (D)

Microthermal Climates (D)Subarctic –

Cool Summer

Figure 10.19

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Polar and Highland Climates

• Extremes of day length between winter and

summer determine the amount of insolation

received

• Low Sun altitude even during the long summer

days is the principal climatic factor

• Light-colored surfaces of ice and snow reflect

substantial energy away from the ground

surface, thus reducing net radiation

Polar and Highland Climates

• High latitudes and polar regions

– Tundra – high latitude and high altitude

– Ice Cap and Ice Sheet – permanently frozen

– Polar Marine – oceanic association

• ~19% of earth’s total surface

• This climate have no true summer�average monthly temps never rises over above 50F

Polar Climates (E)

Arid and Semiarid Climates B

• Dry air in subtropical high-pressure

systems dominates

• Sometimes form in the rain shadow of

mountains

• Continental interiors, particularly central

Asia, are far from moisture bearing air

masses

Dry, Arid, and Semiarid Climates • Permanent moisture deficits

– Arid desert - less that about 35 cm (14 in.)

precipitation per year

– Semiarid steppe - less than about 60 cm (23.6

in) precipitation per year

– They occupy ~35% of earth’s; the most

extensive climate over land.

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Dry, Arid, and Semiarid Climates (B)Desert Landscape

Figure 10.23

Low-Latitude Hot Desert

Figure 10.24

Mid-Latitude Cold Desert

Figure 10.25

Generalized Climate Regions

Figure 10.4