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Glossary of Terms
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1. cirrocumulus
Cirrocumulus are higher level clouds. They are white and in the form of flat sheets but consisting of small globules.
2. altostratus
Altostratus are middle level clouds. Their appearance are that of flat grey bases in the form of sheets. They are usually difficult to photograph because of their low contrast.
3. altocumulus
Altocumulus are middle level clouds. Sometimes altocumulus develop further down and appear like stratocumulus, when in the form of globules. Sometimes they develop cumuliform tops and are then called altocumulus castellanus. Under some conditions, altocumulus form from wind wave motion and appear in the shape of a flying saucer or lens. This is known as lenticular altocumulus.
4. wind
Wind is basically movement of air. Wind can move in any direction, not only horizontal.
5. weather
Weather is the day to day changes in atmospheric conditions. Precipitation, cloud, thunderstorms, floods, tornadoes and so on are all part of weather.
6. water vapour
Water vapour is water in the form of gas. It is invisible.
7. tornado
A tornado is a funnel shaped cloud that connects cloud to the ground. It develops from the cloud and eventually reaches the ground stirring debri and dust.
8. thunderstorm
A large cloud system consisting of downdraughts and updraughts but recognised for its lightning and thunder activity. It can produce light to heavy precipitation, namely rain and hail. The structure and efficiency of its updraughts and downdraughts determine the life span and severity of a thunderstorm. Severe thunderstorms can therefore produce larger hail, strong winds, very heavy rain and sometimes even tornadoes.
9. thunder
Thunder is the sound created from the sudden heating of the air caused by lightning. It can vary from a crashing bang to a rolling sound.
10. temperature
Temperature is the measure of the molecular activity of particles in a substance. In terms of air temperature, the more heat, the faster the molecules move and hence the higher the measure of temperature.
11. stratus
Stratus are low clouds appearing more fragmented and disorganised. They also appear to be fast moving.
12. stratocumulus
Stratocumulus are low level clouds that look like cumulus but extend in a band. Some stratocumulus may also appear as broken flat layers consisting of globules and therefore resemble altocumulus. Sometimes stratocumulus develop higher up and appear like altocumulus.
13. sea breeze
A sea breeze is a wind that flows from the ocean onto the land. It typically develops in the afternoon when the land is hotter than the ocean. During the evening or night, the land normally cools and the breeze stops.
14. rain
Precipitation in the form of liquid water droplets falling from clouds. Rain can vary from light drizzle (small droplets) to heavy rain (large droplets). Heavy rain also has a larger density of larger water droplets.
15. radiation
Radiation is a way heat can transfer through space. Heat from the sun reaches the earth through radiation.
16. precipitation
Precipitation consists of any forms of atmospheric moisture which condense from water vapour. They consist of rain, hail, snow, dew and fog.
17. nimbostratus
Nimbostratus are middle level clouds. They are similar in appearance to altostratus (grey bases and relatively flat) but they do produce precipitation. Sometimes, nimbostratus develops further down in the levels where stratocumulus develop.
18. meteorology
Meteorology is the scientific study of the physical conditions in the atmosphere to make forecasts.
19. meteorologist
A meteorologist is a person who studies meteorology and is associated with making forecasts of weather for various clients such as the public, shipping industry, agricultural industry, building industry and so on.
20. lightning
Lightning is the visible electrical activity observed in thunderstorms. It may occur in bolt to the ground or at the base of the clouds, or sheet flashes in the clouds.
21. heatwave
A heat wave is an extended period of unusually very warm to hot conditions.
22. hailstorm
A hailstorm is a storm that produces any form of hail. It does not necessarily have to be severe.
23. hail
Frozen balls or chunks of ice falling from clouds usually thunderstorms. Thunderstorms reaching great heights or regions of colder air typically produce hail. Hail is largest when the updraughts are sufficiently strong to force small hail upwards through the cloud several times. As they do they grow larger freezing the water droplets that contact making contact on the way up. When the updraught is not sufficiently strong to support the weight of the grown hailstone, it falls to the ground.
24. frost
Frost is frozen moisture in the form of ice crystals forming on the ground. It appears white on the grass increasing in brightness depending on how cold it is at the ground level.
25. fog
Fog is cloud forming near the ground, lake or ocean as water vapour condenses. Depending on thickness, it can reduce visibility.
26. ever changing
Ever changing basically refers to and stresses the importance of different aspects of the weather constantly changing rather than moving unchanged.
27. drought
A drought is an extended period of very low rainfall based on the usual average precipitation.
28. dew
Dew is moisture developing at ground level. It is mostly observed on vegetation such as grass or trees in the mornings when the air is coolest and hence condensation can occur.
29. cumulus
Cumulus are low level clouds in the form of heaped tops resembling cauliflowers.
30. cloud
A region of condensation in the atmosphere making water vapour visible. Different types of clouds develop under various conditions. Cloud is normally categorised based on height in the atmosphere: high, middle and low clouds. Cloud can produce precipitation if conditions are ideal.
31. cloud classification system
A cloud classification system is used to categorise different types of clouds. It is mainly based on the level clouds exist in the atmosphere.
32. climate
Climate is the study of atmospheric conditions over a long period of time in a particular region. For instance, tropical regions have hot and wet climates and deserts are associated with dry climates.
33. cirrus
Cirrus are higher level clouds. They are typically bright white with various shapes. They are very thin such that the sun can easily pentrate. They produce no precipitation.
34. cirrostratus
Cirrostratus are higher level clouds. Like cirrus, they are bright white and transparent. Cirrostratus spread out in the line of the wind. They produce no precipitation.

Document: definit.htm
Updated: 18th March 2008

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