MET Flashcards
If an unsaturated parcel of air is cooled beyond its dew point, what will happen?
It will become saturated and some of the water vapour will condense out, forming clouds.
What is ‘dew point’
The temperature at which a parcel of air is saturated and ahs a relative humidity of 100%.
What is the difference between absolute and relative humidity?
- Absolute humidity is the quantity of water in the air, expressed in grams per cubic metre.
- Relative humidity is absolute humidity in relation to the quantity required for the air to be saturated, expressed as a percentage
What is the troposphere?
The lowest layer of the atmosphere. It is the layer which contains almost all of the water and most of what we think of as ‘weather’.
Complete the sentence:
When air rises, it
cools due to expansion.
At what rate does unsaturated air cool with altitude?
10 degrees C/km.
What type of atmospheric stability results in clear skies?
Absolute stability, where the parcel of air is always cooler than the surrounding air and therefore wants to sink back down to its original altitude.
What does SALR stand for?
Saturated Adiabatic Lapse Rate.
What is it called when air is forced to rise because of two or more air flows meeting?
Convergence.
What is it called when air is forced to rise due to land?
Orographic uplift.
What is a fluffy cloud at low altitude called.
Cumulus.
What does a nimbostratus cloud look like?
A nimbostratus cloud is a flat layer of cloud at low altitude which brings rain.
How might clouds change when a depression is approaching?
As a depression approaches, high clouds will appear and it will thicken and lower as the depression gets closer.
What are squalls?
A sudden and dramatic increase in wind speed, which lasts longer and is more significant than a regular gust. It can also cause a significant shift in the wind direction.
Which air mass forms over Northern Canada and Greenland, and moves directly across the North Atlantic to the UK?
POLAR maritime.
How is an air mass which originates over land termed?
Continental.
What are the characteristics of maritime air?
Maritime air masses are more humid (contain more water) than continental air masses.
