Global energy budgets Flashcards
Why do we get low pressure?
1) Air is rising in some areas, especially where air is heated at the ground
2) Air flows in at the ground to replace rising air
3) Rising air hits the top of the atmosphere and spreads out
4) The air flowing in at the ground is slowed down by friction at the surface
5) This means it is easier for air to leave the area than to come in
Why do we get high pressure areas? (6 points)
1) Air is sinking in some areas
2) Sinking air hits the ground and spreads out
3) Air flows in at the top to replace the sinking air
4) The air spreading out at the ground is slowed down by friction at the Earths surface, but the air flowing in is not
5) This means its easier for air to come into the area than to leave it
6) Therefore we end up with more air, this is high pressure
Is there more or less air in high pressure areas
More
Is there more or less air in low pressure areas?
Less
Is air rising or sinking in high pressure areas
Sinking
Is air rising or sinking in low pressure areas
Rising
Is air at the surface moving away from or into the area at high pressure?
Moving in
Is air at the surface moving away from or into the area at low pressure?
Moving away
What is the typical pressure value at high pressure?
Up to 1500 millibars
What is the typical pressure value at low pressure?
950 millibars
What makes air move?
High and low pressure areas - the Coriolis effect
Does air blow directly between high and low pressure areas or along the pressure contours around these areas?
Along pressure contours in circles, around high and low pressure areas
Which way is air deflected in the northern hemisphere
Deflected to the right
They blow around a low pressure system in an anticlockwise direction in the Northern hemisphere
Which way do winds blow?
From high pressure to low pressure, and if there is a steeper pressure gradient the winds tend to be faster
How do air masses gain their characteristics (winds)
By prolonged contact with the ground or sea surface
What are the source regions for polar air masses?
High pressure systems over continents
Which way do North easterly winds, in the northern hemisphere, and south easterly winds, in the southern hemisphere, blow?
Towards the equator to gain heat
What are air masses classified into?
Continental or maritime, according to where they formed
What does a maritime track of air allow for?
It allows the lower layers of air mass to become saturated with moisture
What does a continental track leave behind?
Leave air mass with low humidity
What are the 6 main air masses that affect the British isles?
- Arctic maritime
- Polar continental
- Tropical continental
- Tropical maritime
- Returning polar maritime
- Polar maritime
What is the source of the arctic maritime air mass?
Arctic
What does the arctic maritime air mass bring?
Wet, cold air - brings snow in winter
What is the source of the polar continental air mass?
Central Europe
What does the polar continental air mass bring?
Hot air brings dry summers
Cold air brings snow
What is the source of the tropical continental air mass?
North Africa
What does the tropical continental air mass bring?
Hot, dry air brings hot weather in summer
What does the tropical maritime air mass bring?
Warm, moist air brings cloud, rain and mild weather
What is the source of the tropical maritime air mass?
Atlantic
What is the source of the returning polar maritime?
Greenland/Arctic via North Atlantic
What does the returning polar maritime bring?
Moist, mild and unstable air bringing cloud and rain showers
What is the source of the polar maritime air mass?
Greenland/Arctic Sea
What does the polar maritime air mass bring?
Wet, cold hair brings cold and showery weather
