Atmosphere and Weather Flashcards
What is meant by the term Albedo?
The proportion of energy reflected back to the atmosphere depending on a surface’s reflectivity
Define reflected solar radiation
The energy from the sun as short wave radiation that is not absorbed by the surfaces
Define sensible heat transfer
Heat exchanged by conduction / convection between warmer and colder bodies or a change in temperature of an object by heat exchange with no phase change
Briefly explain how dew is formed (3)
By condensation of moisture on a surface as the air is cooled to dew point or by contact with a surface losing heat by radiation
Explain why night time temperatures vary across an urban area (5)
- Release of heat absorbed during the day
- Variations in amount of heat absorbed due to surface characteristics e.g. albedo / density
- Heat released from anthropogenic sources e.g. heating and lighting of buildings / power stations / industry / vehicles
- Pollution blanket
- Protection against wind
- Variations in density of buildings (open space)
Briefly describe how some incoming solar radiation is prevented from reaching the earth’s surface (3)
- Absorption from the atmosphere
- Reflection by clouds
- Scattering by dust
Define short wave radiation
Incoming solar radiation
Define long wave radiation
Outgoing terrestrial radiation whereby the earth’s surface has been heated by solar radiation
Briefly explain what is meant by a temperature inversion (3)
An increase rather than a decrease of temperature with height. They can form at the surface e.g. advection cooling or in the upper atmosphere e.g. stratosphere
Define dew point
The temperature at which relative humidity is 100%
Advection fog
Occurs when warm air flows over a cold surface and its temperature is chilled to dew point
Radiation fog
Occurs when the ground loses heat at night by long-wave radiation and chills the air to its dew point
Define mist
Cloud at ground level and occurs when visibility is between 1000-5000m and relative humidity is over 93%
Define fog
Cloud at ground level and occurs when visibility is below 1000m - dense fog occurs when the visibility is below 200m
2 ways condensation can take place
- Cooling of air
2. Addition of moisture into the atmosphere e.g. via sea breeze
When does temperature inversion happen?
When there are relatively calm (high-pressure) conditions and little mechanical turbulence from the wind that causes the air to mix
Why are temperature inversions important?
They influence air quality
When does temperature inversion act as a lid for pollutants?
Under high-pressure conditions and limited air movement - it causes the pollutants to remain in the lower atmosphere next to the Earth’s surface. The cold air at the surface is dense so it will tend to star at the surface.
Only when the surface begins to heat up and in turn warms the air above it, the warm air will be able to rise and with it any pollutants that it may contain
Where are temperature inversions common?
In depressions and valleys - cold air may sink to the bottom of the valley and be replaced by warmer air above it
When does the South Pole receive most insolation
December-January (summer solstice)
What does STHP stand for?
Subtropical high-pressure belts and it is permanent
Which has the greatest seasonal contrast in pressure - land or sea?
Land
How does a cold land mass influence pressure?
It causes high pressure
How does a warm land mass influence air pressure?
It causes low pressure
What does monsoon mean?
Wind reversal
What does ITCZ stand for?
Inter-tropical convergence zone
What is the ITCZ also known as?
The equatorial trough
What is the ITCZ?
A band a few hundred kilometres wide in which winds from the tropics blow inwards, converge and then rise, forming an area of low-pressure
Why do areas that are closer to the equator receive more heat than those that are closer to the poles?
- Insolation is concentrated near the equator but dispersed near the poles
- Insolation near the poles has to pass through a greater amount of atmosphere so there is a higher chance of it being reflected back out to space
Which has a lower SHC - land or water?
Land heats and cools more quickly than water
Why does water heat more slowly?
- It is clear so the sun’s rays penetrate to a greater depth (distributing energy over a larger volume)
- Tides and currents cause the heat to be further distrubted
What does a maritime or oceanic area mean?
An area with coastal influence
What is wind?
Air moving from a high pressure area to a low pressure area
What’s the difference between absolute humidity and relative humidity?
Absolute humidity refers to the amount of water in the atmosphere whereas relative humidity refers to the water vapour present expressed a s a % of the max. amount of air that the temperature can hold
How would insolation and albedo vary between a polar ice cap and a tropical rainforest?
A polar ice cap would have a lower insolation but a higher albedo whereas a tropical rainforest would have a higher insolation but a lower albedo
Explain why a coastal area may have a different temperature from a continental area of the same latitude
The ocean takes up heat and gives it back much more slowly than the land.
In which direction does the monsoon blow in July and January?
In July - Northwards into India (the southeast monsoon) and in January - southwards towards Australia (the northeast monsoon)
What is meant by the term “specific heat capacity?”
The amount of heat needed to raise the temperature of a body by 1 degree C
What happens during evaporation?
Water changes from a liquid to a gas, and heat is absorbed
What happens during condensation?
Water changed from a gas to liquid as latent heat locked in the water vapour is released, causing a rise in temperature
What is the significance of the “condensation level”?
It is the altitude at which relative humidity reaches 100% and therefore condensation occurs, forming the base of clouds
Suggest 3 different causes of the initial uplift of the parcel of air
Uplift can be caused by convectional heating, frontal activity or relief (orographic uplift)
Define the terms instability and stability
Instability refers to rising air (low pressure) whereas stability refers to descending air (high pressure)
Characteristics of instability
- Rising air
- Low pressure conditions
- Cloud formation
- Rain and wind
Characteristic of stability
- Dry descending air
- Calm conditions (high pressure)
- Relatively clear skies
When does instability occur?
When a parcel of air is warmer and therefore less dense than the air above, causing rising and expansion - ELR > DALR
When does stability occur?
When a parcel of air is displaced upwards - it immediately gets cooler and denser and sinks - ELR < DALR and the SALR
Under which atmospheric conditions (stability or instability) do mist and fog form and why?
During stable high-pressure air conditions because if there is low-pressure system, the winds will prevent mist and fog from forming by mixing the air
In terms of global warming, explain why there is an increased risk of hazards in coastal cities
As a result of increased temperatures, some glaciers and ice caps will begin to melt, posing a risk of flooding to low-lying coastal cities. In addition, increased atmospheric energy will mean that storms will increase in frequency and intensity, also adding to the risk of coastal flooding.
Describe the main differences between the climates of urban areas and those of their surrounding rural areas
Urban climates are typically warmer, less windy, have more cloud cover and more rain than rural areas
What is meant by the term “urban heat island”?
A pattern of temperature in large urban areas in which the maximum is found near the city centre. There is a plateau across the suburbs and a temperature cliff between the suburban and rural areas where temperatures are lower than the urban area.
What is meant by “anticyclone”?
A high-pressure system
What is meant by “aspect”?
The direction in which a slope faces
What is meant by “continentality”?
A climate characteristic of a continental area - very hot summers + very cold winters + low rainfall
What is meant by the “Coriolis effect”?
An effect that causes any body that moves freely with respect to the rotating Earth to veer to the right in the Northern hemisphere and to the left in the Southern Hemisphere
What is meant by “Frontal rainfall?”
The rain formed when warm air is forced to rise over denser cold air when two different air masses meet at a front
What are Jet streams?
Narrow, fast-flowing currents of air found near the tropopause
Explain why temperatures recorded over land often differ from those recorded over sea at the same latitudes. [4]
This is due to the different specific heat capacities of land and sea. It takes more radiation to heat up an equivalent volume of sea water than land. Thus in summer the sea is generally cooler than the land in equivalent latitudes. Sea water retains its heat longer than land, thus in winter the sea is warmer than the land.
