Download Weather and Climate - the Essentials!

Weather and Climate - the Essentials!
The examiners nearly always ask you to explain the difference between WEATHER and CLIMATE:Weather is the day to day conditions of the atmosphere whereas climate is the long term conditions
that prevail (the usual) in a particular region.
MICROCLIMATES – there is always at least one question within the CE section on weather and
climate that is devoted to microclimate; sometimes virtually all the question can focus on it.
What is a microclimate? The climate of a very small or restricted are e.g. a house garden.
What factors affect microclimate? There are a number of factors:Effect of hedges/SHELTER
Effect of SHELTER
Effect of PHYSICAL
FEATURES
Effect of SURFACE
Effect of BUILDINGS
What is the WATER CYCLE? How does it work?
Effect of ASPECT
You will need to know about the components (parts) of the WATER CYCLE:Condensation - the opposite of evaporation. Condensation occurs when a gas is changed into a
liquid.
Infiltration - Infiltration is an important process where rain water soaks into the ground, through the
soil and underlying rock layers.
Surface Runoff - Much of the water that returns to Earth as precipitation runs off the surface of the
land, and flows down hill into streams, rivers, ponds and lakes.
Evaporation - the process where a liquid, in this case water, changes from its liquid state to a
gaseous state.
Precipitation - When the temperature and atmospheric pressure are right, the small droplets of
water in clouds form larger droplets and precipitation occurs. The raindrops fall to Earth.
Interception – when plants and trees intercept precipitation
Transpiration - As plants absorb water from the soil, the water moves from the roots through the
stems to the leaves. Once the water reaches the leaves, some of it evaporates from the leaves,
adding to the amount of water vapour in the air. This process of evaporation through plant leaves is
called transpiration.
Groundwater flow – when water runs through the soil.
Throughflow – when rainwater runs through rock.
Types of RAINFALL
There are three types (the CE examiners usually ask you to draw and annotate one of these):Relief rainfall
Convectional rainfall
When the land warms up, it heats the air above it. This
causes the air to expand and rise. As the air rises it
cools and condenses. If this process continues then rain
will fall. This type of rainfall is very common in tropical
areas but also in areas such as South East England
during warm sunny spells.
Prevailing winds bring warm, moist air to the
western British Isles.
Air is forced to rise over high areas.
Air cools and condenses.
Clouds form and it rains.
Air descends on the other side of the mountains.
It warms up and therefore becomes drier.
Frontal rainfall
You will also need to know about temperature and rainfall variations from place to place in the
British Isles:-
The maps below show variations (differences) in Rainfall, Relief and Temperature for Great Britain.
The main points you have to remember for your Common Entrance Examination are:






There is more rainfall in the west and north of the country, where there is higher land. Much
of this rainfall is RELIEF RAINFALL.
The temperature is higher in the south of the country because this area is closer to the
EQUATOR. This is the effect of LATITUDE.
There is more rainfall in the west compared to the east because of the influence of the
ATLANTIC OCEAN. A warm ocean current called the NORTH ATLANTIC DRIFT leads to more
moisture in the air coming from the west. Much of this rainfall is FRONTAL RAINFALL.
The east of the country has less rainfall due to being in the RAINSHADOW of the hills to the
west.
The temperature in the west of the country is higher in winter due to the warming effect of
the NORTH ATLANTIC DRIFT.
The temperature falls as you go higher up. Therefore, it tends to be colder in the hills of the
west and north. This is the effect of ALTITUDE on temperature.
Temperatures increase further inland during summer but are warmer on the coast during
winter. This is due to the ocean taking longer to heat up and lose heat compared to the land.
Polar Maritime air masses
bring wet and cool
conditions to the north
west of the country
Arctic Maritime air
masses bring rain and
snow in winter
Polar Continental air masses
bring cold weather in winter and
warm weather in summer
North Atlantic Drift is a warm
current which begins in the Gulf
of Mexico – warms the west of
the country in particular
Prevailing (usual) winds from the South West bring
warmth and moisture (rain) to the west of the
country. Tropical Maritime air masses bring warm,
moist air to the west too.
Places
inland are
warmer in
summer and
colder in
winter
The east of the country is in a
Rainshadow – most of the
rain from the east has fallen
over the hills to the west
The south is generally warmer than the
north due to Latitude – the south is closer
to the Equator and the dry Tropical
Continental air mass