Rainfall is caused by air rising; as the air rises it cools and it is able to hold less water; condenstation occurs, clouds form and then precipitation falls.

Different Typs of Rainfall (different reasons air rises)

1. Relief Rainfall  - air goes towards a mountain, it is therefore forced to rise.
2. Convectional Rainfall - air heats up by contact with warm ground; it is less dense so it then rises.
3. Frontal Rainfall - at a warm front, warm air rises over cooler air. At a cold front, the cold air forces warmer air upwards.

Human Development Index, is a composite development indicator. Composite because it is made up of a number of other indicators.

The components that make up the Human Development Index are:

• A long and healthy life: Life expectancy at birth
• Education index: Mean years of schooling and Expected years of schooling*
• A decent standard of living: GNI per capita (PPP US$)

Countries are given a HDI score which is a number from 0 to 1. They are then grouped by this score into four categories:

• very high human development
• high human development
• medium human development
• low human development

The global pattern of HDI is shown on the map below:

Source of the above image: http://en.wikipedia.org/wiki/File:2011_UN_Human_Development_Report_Quartiles.svg

In 2011 the highest ranking country according to the Human Development Index was Norway (0.943); and the lowest was the Democratic Republic of the Congo (0.286).

More information can be found on the United Nations Human Development Project website: http://www.undp.org/

*This is a change for the 2011 HDI Index, prior to 2011 the Education aspect was measured by the adult literacy rate (with two-thirds weighting) and the combined primary, secondary, and tertiary enrollment ratio (with one-third weighting).

Choropleth Map - a thematic map in which areas are shaded or patterned in proportion to the measurement of the statistical variable being displayed on the map, such as populaiton density.

The choropleth map provides an easy way to visualise how a measurement varies across a geographic area or it shows the level of variability within a region.

Examples of Choropleth maps:

Choropleth maps will use graduated colour ramps, this gives an immediate visual impression of the pattern without seeing the key; examples of colour ramps are:

(download)

Click here to download:

choropleth-maps-ufaaoFEnxzxFHdBjldsd.zip (2 KB)

River - A large natural stream of water flowing in a channel to the sea, a lake, or another stream.

The World's Longest Rivers

1. Nile - 6,650 km (4,135 miles) - Africa - Drains: Uganda, Tanzania, Kenya, Rwanda, Burundi, Egypt, Democratic Republic of Congo, Ethiopia, Eritrea, and Sudan.

2. Amazon - 6,400 km (3,980 miles) - South America - Drains: Peru, Brazil, Guyana, Bolivia, Venezuela, Colombia, and Ecuador.

3. Yangtze - 6,300km (3,917 miles) - Asia - China.

4. Missippi-Missouri - 6,275km (3,902 miles) - North America - USA.

5. Yenisei-Angara-Selenga - 5,539km (3,398 miles) - Eurasia - Russia and Mongolia.

6. Huang-He (Yellow River) - 5,464 km (3,398 miles) - Asia - China

7. Ob-Irtysh - 5,410 km (3,364 miles) - Euraisa - Russia, Kazakhstan, China, and Mongolia.

8. Congo-Chambeshi - 4,700 km (2,922 miles) - Africa - Rwanda, Burundi, Zambia, Cameroon, Tanzania, Republic of the Congo, Democratic Republic of the Congo, Angola, Central African Republic)

9. Amur-Argun - 4,444 km (2,763 miles) - Eurasia - Russia, People's Republic of China, Mongolia.

10. Lena - 4,400 km (2,736 miles) Eurasia - Russia.

It is disputed whehter the Amazon is actually longer than the Nile; for more informaiton on this debate see here.

The aim of this Posterous Blog is to post a different geographical concept or idea everyday.

The inspiration is a word a day calendar; except this blog will soley focus on geographical concepts.

It will start today January 2nd 2012; and run to at least January 2nd 2013.

Graeme

My main blog/website can be found at: http://www.graemeeyre.info