Clouds Flashcards
What is a cloud? How do clouds form? Why are there so many different kinds of clouds? How does air rise?
What is a cloud?
water droplets/ice crystals suspended in the atmos. by upwards air drafts
How do clouds form?
clouds form as air rises, cools and water vapour condenses (water in a gas form that turns into liquid)
How does air rise? (4 ways)
1) Orographic Lift
2) Convergence
3) Convection
4) Frontal Lift
Explain how air rises during Orographic Lift
1) forced ascent of warm, moist oceanic air over a mountain barrier (produces orographic precip & rain shadow effect)
2) as the air moves up the mountain barrier, it loses moisture through precipitation
3) as it decends, the far slope is warmed & may lead to Chinook Conditions
Where does Orographic lift occur?
Mountains
- Maui
- North Shore Mountains
Explain how air rises during Convergence
-low pressure system
-air rises from opposing airflows
(low air pressure come together and pushes up)
Explain how air rises during Convection
- warm air rises because they are less dense than the surrounding cooler air
- where the excess water vapour in rising air parcels condenses to form a cloud.
Define Weather
“State of the atmosphere at a place and time”
-short term
Define Climate
“Weather conditions at a place averaged over a long period (several decades)”
- long term
- ice age
How are clouds classified?
- based on:
1) HEIGHT
2) FORM
What are the 3 categories describing height?
1) LOW - bases below 2000 m
2) MIDDLE - bases btw. 2000m-7000m
3) HIGH - bases btw. 5000m-14,000m
What are the 4 FORMS of clouds and their latin meaning?
1) CIRRUS - curl of hair
2) CUMULUS - heap
3) STRATUS - layer
4) NIMBUS - rain
What are the characteristics of LOW Clouds?
- composed mostly of water droplets
- cover the mountain tops
What are the 4 types of Low Clouds?
1) Stratus
2) Stratocumulus
3) Cumulus
4) Cumulonimbus
What are the characteristics of a STRATUS Cloud? (low)
- sheet of cloud
- high fog (above ground)
- deep enough to produce drizzle/light snow
What are the characteristics of a STRATOCUMULUS Cloud? (low)
- most common
- sheet of cloud w/ well defined base
- can produce light precip.
What are the characteristics of a CUMULUS Cloud? (low)
- detached heaps of clouds w/ mounded tops and flat bottoms
- fair weather, form as warm air rises
- can grow vertically + produce precip.
What are the characteristics of a CUMULONIMBUS Cloud? (low)
- large heaped clouds (low altitudes–>troposphere)
- heavy precip., short duration
- hail, thunder and lightning
What are the characteristics of MIDDLE Clouds?
-composed of water droplets/ice crystals
What are the 3 types of MIDDLE Clouds?
1) Altostratus
2) Altocumulus
3) Nimbostratus
What are the characteristics of a ALTOSTRATUS Cloud? (middle)
- sheet cloud (watery sun)
- associated with the approach of warm front
- light precip.
What are the characteristics of a ALTOCUMULUS Cloud? (middle)
- puffy grey masses that form in groups
- associated with thunder storms (warm fronts)
What are the characteristics of a NIMBOSTRATUS Cloud? (middle)
- sheet of cloud thick enough to block out sun/moon
- warm front
- steady precip. moderate intensity
- ex. Vancouver
- can occur in both low and middle
What are the characteristics of HIGH Clouds?
- thin (low water content)
- composed entirely of ice crystals
What are the 3 types of HIGH Clouds?
1) Cirrus
2) Cirrostratus
3) Cirrocumulus
What are the characteristics of a CIRRUS Cloud? (high)
- streaks scattered across the sky
- fair weather –> approach warm front
- form in jet stream (turbulence)
- “fall streaks” or “mare’s tails”
What are the characteristics of a CIRROSTRATUS Cloud? (high)
- sheet of cloud, veil over the sky, thin enough to see sun/moon
- approach of warm front
- creates halo around sun/moon
What are the characteristics of a CIRROCUMULUS Cloud? (high)
- long rows, sheet of cloud broken into tiny clumps
- smaller than altocumulus
- usually seen in winter (cold temp)
