Section 4B: Water in the Atmosphere Flashcards
Define:
Absolute Humidity.
Relative Humidity.
Saturation.
Dew Point.
Absolute Humidity
Absolute humidity is the total mass of water vapor present in a given volume or mass of air.
Relative Humidity
Relative humidity is the ratio of the current absolute humidity to the maximum possible absolute humidity (saturation) at that temperature.
Saturation
Saturation refers to the state when air contains the maximum possible amount of water vapor at a given temperature and pressure.
Dew Point
The dew point is the temperature at which air becomes saturated with water vapor, causing condensation to form.
Explain why the leeward side of a mountain range may be warmer and drier than the windward side.
- Prevailing winds pick up moisture over water bodies.
- Windward side of the moutain, air rises and cools and changes to rain or snow.
- Leeward side of the mountain, air descends and warms, moisture remains in the atmosphere as water vapour, hence the drier conditions.
Briefly explain the hydrological cycle.
The continuous movement of water through different reservoirs on Earth, driven by the sun’s energy.
Condensation occurs if the air is cooled below its dew point. List different ways this cooling can occur.
- Adiabetic cooling
- Contact with colder air masses
- Radiation of heat from the upper layers of air
- Contact with cold surfaces
List and define different types of precipitation.
Water forms when water vapor in the atmosphere condenses into droplets heavy enough to fall to the ground.
Snow forms when water vapor condenses directly into ice crystals in cold clouds.
Ice forms when snowflakes partially melts and refreezes.
Define ‘visibility’.
The distance or clarity with which objects can be seen under given atmospheric conditions.
Briefly explain the formation of advection fog.
Advection fog forms when warm, moist air moves horizontally over a colder surface, such as a cold ocean current or snow/ice-covered ground. As the warm air comes into contact with the colder surface, it cools down, causing the moisture in the air to condense into tiny water droplets, forming fog
Briefly explain the formation of radiation fog. List the favourable conditions.
Briefly outline various causes of poor visibility.
Explain, with the aid of a sketch, how the time of occurrence of advection fog could be predicted.
Define smog and orographic fog.
What are the four main types of clouds classified according to their appearance? Briefly define each type. State the weather conditions generally associated with each type.
Using a table, list the ten main types of clouds according to their heights. Show what these heights are. Also, show any special clouds.
List the four main ways of cloud formation. Briefly explain each one of these methods with the aid of sketches.
Briefly describe ‘Thunderstorms’. The description should cover, favourable conditions for formation, the process of formation, the structure of it and the weather associated.
