scaffolding activity teacher's guide
Moisture is required for precipitation to develop. As a parcel of air rises,
water vapor will cool and condense, forming tiny
water droplets. If there is a lack of moisture, there will not be enough water
droplets to form a cloud, let alone precipitation.
2) They are lifting mechanisms, responsible
for generating upward motion necessary for precipitation to
An air parcel cools as it rises because it expands due to decreasing
pressure with height. This expansion causes the air to cool and
the water vapor condenses into tiny
water droplets. With continued condensation, clouds develop and eventually
Boulder, CO, a city on the east side of the Rockies.
Downslope winds are expected.
Downslope winds (or wind blowing down the mountain) tend to be very dry,
warming as it descends, creating an
unfavorable environment for
the development of precipitation (since rising air in the presence of
downslope winds is unlikely).
A cold front is approaching from the west, but the air both ahead of
and behind the front is very dry.
||The cold front is an important lifting mechanism,
but there isn't enough moisture for precipitation to develop.|
A warm front is approaching and the air behind and ahead of the front
is very moist.
With moisture present and lifting forced by
"overrunning" of the warm
front, these are favorable conditions for precipitation to develop.
Upslope winds are expected in Boulder, CO and
the air has been
very moist for the past couple of days.
With moisture available, winds blowing up the mountain will provide
the lifting of air (since air can't go through the mountain, it must
go up and over), and this combination creates a favorable environment for
the development of precipitation|
The trend for the latest
batch of precipitation is a steady eastward movement of 30 miles/hour.
The latest position is roughly 700 west of here. Will precipitation arrive
within 24 hours?
Using mathematics, at 30 miles/hour the precipitation
should move 720 miles over a 24 hour period, which means that it will have
reached us by then (though just barely).