The rain-shadow effect
Sem-arid conditions in Save Valley are due to the Rain-shadow effect. Image by Youth Delegates ZIMSEC O Level Geography Notes: Rain Shadow Effect
We have already looked at the formation of relief rainfall elsewhere. The […]
January 2023
Stevenson’s screen
An open Stevenson screen showing the instruments it houses. Image by Hubhomedesign. ZIMSEC O Level Geography Notes: Stevenson Screen
A Stevenson screen is a prominent feature on most weather stations.
- It is used to house weather instruments, for example the […]
Weather symbols/ Synoptic Charts
ZIMSEC O Level Geography Notes: Weather Symbols and Synoptic Charts
- After weather measurements have been taken at weather stations
- they are then plotted onto synoptic charts.
- These charts make use of special symbols as a form of pre-agreed shorthand that is used to show the weather conditions at a given place at a […]
Humidity
Wet and dry bulb thermometer. Image by TradeIndia ZIMSEC O Level Geography Notes: Humidity
-a quantity representing the amount of water vapor in the atmosphere.
- It is measured using a hydrometer.
- The wet and dry bulb thermometer is also known as a psychrometer.
- Weather satellites can […]
People and Weather
People and Weather. Image via CNN. ZIMSEC O Level Geography Notes: People and Weather
- The earth’s climate and weather conditions have been changing constantly throughout the earth’s Geological Timescale.
- This has in turn had an impact on people’s cultures, history and current economical and social […]
An aneroid barometer. Image Deliberate Changes to weather: Cloud seeding, Dam construction, Greenhouses
Greenhouses are used to grow crops like tomatoes in areas that suffer from frost or during winter. Image via Sustainablenantucket. ZIMSEC O Level Geography Notes: People and Weather: Deliberate Changes
Greenhouses
- These are used […]
Clouds
Clouds. Image by ThirdScribe. ZIMSEC O Level Geography Notes: Clouds
Refers to the fraction of the sky obscured by clouds when observed from a particular location. Okta is the usual unit of measurement of the cloud cover. Sky conditions are estimated in terms of how many eighths of the […]
Unintentional changes to weather
ZIMSEC O Level Geography Notes: People and Weather: Accidental Changes
Acid Rain
- The smoke from burning fuels and chemical industries rises into the air and mixes with water vapour.
- When the rain falls down it becomes acidic.
- The acid rain is a weak acid made up of sulphuric and nitric acids.
- Over, a long time (years for example), the rain […]
Wind direction and speed
A cup anemometer and windvane. Image by Noaa.gov. ZIMSEC O Level Geography Notes: Wind direction and speed.
Wind is the movement of air across the earth’s surface due to differences in pressure between two regions. Air moves from high pressure regions to low […]