JDMcDsblog

This page contains detailed lesson notes for the S2 Global Studies course. Use them to help revise or to catch up on any work you have missed through absence/music lessons. etc

Added 21.1.09

Heading Phoenix; a Desert City

Phoenix lies in  the broad valley of the Salt River on the Colorado Plateau, a large upland area in the deserts of South West USA.  It is surrounded by mountains. The flat valley has made it easy to build on.

Why did people move to Phoenix?

• sunshine (4200 hours a year)
• winter warmth
• dry air (in 19th Century thought this would cure diseases)
• irrigation schemes and water supplies, from Colorado River
• air conditioning-this allowed people to cope with the stifling summer heat-many wealthy people moved to Phoenix, especially to Sun City
• transport links to the rest of the USA
• mass tourism became important; many hotels, leisure centres, golf courses built

Fountain in Phoenix; Where do they get their water?

Problems of growth:

Many of these are like the problems of another big city, Los Angeles

• 19 hecatares of desert taken over by building works every day
• too many cars-pollution
• clear desert air badly polluted by smog
• increased crime
• decline in industries
• increasing water shortages

Task; Comparing Two US Cities

In your jotter, copy and complete  table to compare Phoenix (p149-151) and Los Angeles (page 136-137)

Week beginning Monday 12th January

Aim:

1. To describe and give reasons for the climate in Arizona

2. To identify and describe typical desert landforms

Heading: Desert Climate: Phoenix, Arizona

Copy and complete:

Arizona has an ARID climate. The total rainfall is 190 mm. No month has a lot of rain. The wettest months are July and August  but even then, only 25 mm falls, much of it as thunderstorms The driest months are May and June

The temperature ranges from 11 C_ in  January to a high of 33 in July These are average values; it can get much hotter.

Heading: Why is there so little rainfall in Phoenix?

Location: lies inland, a long way from sea. Air flowing over Arizona is dry (low humidity)

Rain Shadow: mountains protect Arizona from rain bearing air streams.

Thunderstorms can bring heavy downpours especially in July-September

Pressure: High Pressure brings dry air

Why is it so hot?

Arizona is at a much lower latitude than Britain. The sun’s rays are much more intense and heat up the ground. The bare rocks and sand heat up quickly. There is often HIGH PRESSURE. This means that air tends to descend. Descending air is DRY AIR. There are very FEW CLOUDS, so long hours of SUNSHINE.

Why does it get cool at night?

In the desert, there are few clouds and little moisture in the air. This allows all the heat stored in the ground to be RADIATED into space.

Week beginning Monday 19th January

Heading: Landforms in the Desert.

Paste this diagram into your jotter

Add caption; Block diagram of typical desert landforms.

Wind and Desert landforms

 Many features in the desert are formed by strong winds. The wind picks up sand grains and moves them. The main features you need to know are:

1. Sand plains
2. Mushroom rocks
3. Sand Dunes
4. wadi

1. Sand plains

The most extensive landform is most deserts are plains. A plain is a broad, flat, level expanse of low lying land. In deserts the wind blows over plains, removing the sand and leaving behind loose stones and gravels. The sand is carried by the wind until it piles up as dunes or blows against rocks to erode them into strange shapes. This is called Wind erosion

2. Mushroom Rock

Copy this diagram into your jotter:

TASK use the handout to suggest how mushroom rocks are formed.

3.  Sand dunes

4. Wadi

Wadis are drv valleys or river channels, formed by water that only flows in exceptional conditions, eg after a heavy thunderstorm. Wadis are generally dry year round except after a rain. The desert environment is characterized by a sudden but infrequent heavy rainfall often resulting in flash floods.  Wadis often have steep slopes. Nomadic and pastoral desert peoples will rely on wadis for water and seasonal vegetation for their livestock.

Further information: click here to visit Desert USA website