The measurement of surface temperature is made:
At ground level.
At approximately 10 metres above ground level.
At approximately 4 feet above ground level.
At approximately 4 metres above ground level
Cloud cover will reduce diurnal variation of temperature because:
Incoming solar radiation is partially reflected back to space and outgoing terrestrial radiation is reflected back to earth.
Incoming solar radiation is re-radiated back to space and atmospheric heating by convection will stop at the level of the cloud layer
The cloud stops the sun rays getting through to the earth and also reduces outgoing conduction.
Incoming solar radiation is partially reflected back to space and outgoing terrestrial radiation is mostly re-radiated from the cloud layer back to the surface.
Most accurate temperatures above the ground level are obtained by:
Tephigram
Aircraft reports
Temperature probes.
Radio sonde.
The diurnal variation of temperature is:
Greater over sea than overland
Less over desert areas than over temperate grassland.
Reduced anywhere by the presence of cloud.
Increased anywhere as wind speed increases.
Over continents and oceans, the relative temperature conditions are:
Warmer in winter over land, colder in summer over sea
Colder in winter over land, warmer in winter over sea.
Cold in winter over land and sea
Warmer in summer over land and sea.
The process of change of state from a liquid mass to a gas mass is:
Condensation in which latent heat is released.
Evaporation in which latent heat is released
Condensation in which latent heat is absorbed
Evaporation in which latent heat is absorbed by the mass
Air is classified as dry or saturated according to its relative humidity. If the relative humidity were 95% the air would be classified as
Conditionally saturated.
Not saturated.
Saturated
Dry
On a wet bulb thermometer in an unsaturated atmosphere there will be a reduction of temperature below that of the dry bulb thermometer because:
Heat is absorbed during the process of condensation.
Heat is released during the process of condensation.
Heat is absorbed by the thermometer during the process of evaporation
Heat is released from the thermometer during the process of evaporation.
Relative humidity is:
Air temperature over wet bulb temperature * 100.
Air temperature over dew point temperature * 100.
The actual mixing ratio of water vapour in a sample of air over the maximum mixing ratio of water vapour that this sample can contain * 100
The maximum amount of water vapour that a sample of air can contain over the actual amount of water vapour the sample does contain * 100.
Absolute humidity is
The number of water droplets in a given quantity of air
The mass of water vapour that a volume of air holds
The maximum amount of water vapour that a given quantity of air can hold.
The maximum number of water droplets that a given quantity of air can hold.
Wet bulb temperature would normally be lower than the dry bulb temperature because
condensation causes a release of latent heat.
evaporation causes cooling of the bulb.
latent heat is absorbed by the bulb thermometer.
of condensation on the muslin wick of the bulb
The wet bulb temperature
Is measured using a hydromete
Is the minimum temperature to which a thermometer bulb can be cooled by the evaporation of water
Measures the dew point of air
Is the minimum temperature reached by the surface of the earth as measured by a thermometer placed 1.2 metres above the ground.
Which one of the following statements relating to atmospheric humidity is correct:
If the air temperature falls then the absolute humidity must increase
The absolute humidity is the mass of water vapour contained in unit volume of air.
The diurnal variation of dewpoint temperature is greatest when skies are clear at night
The dewpoint temperature is the temperature indicated by the wet bulb thermometer.
When condensation takes place, the higher temperature, the _____ the amount of latent heat_____:
lesser released
grater absorbed
greater released
lesser absorbed
When water vapour changes to ice:
Latent heat is absorbed.
Specific heat is released
Latent heat is released.
Specific heat is absorbed.
Throughout the 24hrs of a day the Relative Humidity can be expected to:
Increase during the day and decrease at night.
Stay reasonably constant throughout the 24 hours.
Reduce during the day and increase at night.
Only change with a change of airmass.
During a night with a clear sky, surface temperature will_____RH will_____ and dewpoint will_____:
Fall, rise rise
Rise, rise, fall.
Fall, rise, remain the same.
Fall, fall, remain the same
A change of state directly from a solid to a vapour or vice versa is:
Insolation
Condensation
Evaporation
Sublimation
The instrument used for measuring the humidity of air is a:
Hydrometer
Hygrometer
Wet bulb thermometer
Hygroscope
The process of change of state from a gas to a liquid is:
Evaporation in which latent heat is absorbed.
Evaporation in which latent heat is released.
Condensation in which latent heat is absorbed.
