Assignment Questions

Question 1

in the troposphere, the average temperature drop is __C per km

Answer 1

6.5

Question 2

What is the pressure (kPa), temperature (0C) and density (kg/m3) of the “standard atmosphere” at sea level?

Answer 2

Pressure = 101.325 kPa
temperature = 15C
density = 1.2 kg/m3

Question 3

how can liquid water exist above 100C deep in the ocean?

Answer 3

100C is the boiling point of water at sea level.
The boiling point temperature decreases as pressure decreases, and it increases as pressure increases.
So, under this high-pressure environment, the
boiling point of water is higher than what it is at sea level.

Question 4

You climb into a hot-air balloon in Edmonton and before you get in you note that the
temperature on the ground is 24C. You ascended 2.5 kilometers.
You descend to the exact place where you launched. You notice no
precipitation/ clouds/ evaporation. What temperature do you measure?

Answer 4

The dry adiabatic process is reversible, so without precipitation, cloud formation or
evaporation, the temperature after you descend will be the same as the initial
temperature, i.e., 24C

Question 5

describe the importance of droplet radius in terms of whether a
small liquid cloud droplet (a radius of ≈ 0.1 μm) grows or evaporates:

Answer 5

The smaller the droplet radius the greater the evaporation (the Curvature Effect) and so the higher the RH of the cloud would have to be in order for this drop to grow. So this droplet would likely evaporate if not for the solute effect.

Question 6

describe the importance of solutes in the droplet in terms of whether a
small liquid cloud droplet (a radius of ≈ 0.1 μm) grows or evaporates:

Answer 6

Solutes reduce the evaporation from the droplet and allow it to grow by
condensation from water vapour in the cloud. The higher the solute content
the easier it is to grow the droplet (and hence the lower the RH needs to be
within the cloud).

Question 7

describe the importance of relative humidity in the cloud in terms of whether a
small liquid cloud droplet (a radius of ≈ 0.1 μm) grows or evaporates:

Answer 7

The higher the RH the easier it is to grow a droplet, but it must make it to
the peak of its Kohler curve in order to reach activation. Beyond the peak
of the Kohler curve the necessary RH for growth is less than that at the
peak, so the droplet will grow rapidly without bounds.

Question 8

which of the following are not important to the growth of ice particles
- solutes
- relative humidity in the cloud
- droplet radius

Answer 8

solutes

Question 9

You measure the surface temperature to be T= 22°C and the surface dew point
temperature to be Td = 12°C.
What’s the height of the cloud base (in m)?

Answer 9

LCL= 125(T-Td)
LCL= 125(22-12)
LCL= 1250m

Question 10

Describe how long wave radiation processes can lead to the eventual breakup
and demise of this cloud

Answer 10

The base of a cloud absorbs long wave radiation coming up from the
surface below (warming) whereas the cloud top radiates long wave up to space (cooling). So clouds cool on top and warm on the bottom, meaning
they become convectively unstable and overturn, which mixes them with
the drier environment, which means they will evaporate/dissipate.

Question 11

You observed the surface winds have been blowing parallel to the coast of
Eastern Canada from south to north for days, but then they suddenly become
easterly.
Would you predict fog in your forecast? And if so, what type, why and in which direction
would predict it to travel?

Answer 11

Yes, you should predict an advection fog in your forecast. As the winds shift to
the Easterly, from ocean currents it flows over the relatively warm Gulf Stream
and then the cold Labrador Current. This change in temperature creates
advection fog, which blows towards the East Coast with the wind direction.

Question 12

Wind speed in Edmonton is 22.5m/s.
If the same gradients existed over Calgary, would the winds be stronger or
weaker (and explain why)?

Answer 12

Calgary is further south than Edmonton, so the coriolis force would be smaller
there. From our equation, we can see that means our winds would be faster.

Question 13

How would a higher tilt of earth (eccentricity) affect the strength of the westerly jet streams?

Answer 13

A higher tilt means greater seasonality. The strength of the jet stream is
dependent on the meridional temperature gradient: the greater the gradient is the
stronger the jet stream will be. With a higher tilt, the higher latitudes have the
greatest change, getting colder in the winter and warmer in the summer. So the
jets will be stronger.

Question 14

How would a higher tilt of earth (eccentricity) affect the cyclones produced by the jet streams?

Answer 14

The stronger the jets, the more cyclones they produce. So there would be more
cyclones at midlatitudes.

Question 15

It’s a nice sunny afternoon and you notice some fair-weather cumulus clouds moving toward the east. You also note some
alto-cumulus clouds traveling towards the northeast.
Should you bring a light or a heavy jacket if you go for a hike?

Answer 15

take a heavier jacket. The directional difference between the cloud levels (fair weather cumulus being low clouds and
alto-cumulus clouds being mid-level clouds), indicate that the winds are backing
with height, which is an indication of cold air advection, so you know the temperature is going to fall soon.

Question 16

A 250hPa chart shows an upper level ridge over the BC coast, and an upper-level trough over western Ontario.
What will the weather be in BC?

Answer 16

BC is below the jet stream winds that are coming out of a ridge, so they are decelerating. Decelerating upper winds imply upper level convergence and descending air, so clear skies, high surface pressure and little
likelihood of precipitation.

Question 17

A 250hPa chart shows an upper level ridge over the BC coast, and an upper-level trough over western Ontario.
What will the weather be in ON?

Answer 17

ON is below jet stream winds that are coming out of a trough, so they are accelerating. Accelerating upper-level winds imply an upper level divergence and ascending air, so cloudy skies, a low surface pressure and higher
likelihood of precipitation.

Question 18

You notice some high cirrus clouds in the sky, and later your location is
covered by low-level nimbostratus clouds with light, persistent rain. Then you notice the wind direction veers in a clockwise direction from southeasterly to southwesterly, and the temperature increases but the rain
ends.
Explain what just happened at your location

Answer 18

A warm front just passed over us. High cirrus clouds are an indicator of an
approaching warm front. Veering winds are an indicator of the front passing overhead, and the rise in temperature indicates it
was a warm front.

Question 19

After a day or two of nice, clear air with warm temperatures, you hear some
thunder in the distance and you see
extensive towering cumulus and cumulonimbus clouds. After a couple of
hours you go outside and find it cold but clear
Explain what just happened at your location

Answer 19

A cold front just passed over, and the fact that the temperature drops and the skies cleared is an indicator that the cold front has passed over your location

Question 20

Hudson Bay freezes and melts annually. During the spring when there is
open water, describe how this open water affects the stability of the cP air
mass flowing over it

Answer 20

Open water acts as a heat and moisture source for cP air. This added energy can
destabilize the air mass. So one would expect snow downwind from the open
water source.

Question 21

Is the vertical shear (i.e., a change in wind speed with height) good or bad
for a hurricane? Explain why

Answer 21

Bad. Strong vertical shear over the Atlantic prevents a hurricane from forming
since it needs extensive and coherent vertical convection over a large distance
without much slant to it.

Question 22

Is vertical wind shear good or bad for a mature thunderstorm? Explain
why

Answer 22

Good. The updraft and the downdraft need to be physically separated in order to
get the flow of warm moist air up into the higher troposphere so it can precipitate.
The difference from a hurricane is that it’s large scale and the motion is dominantly horizontal, whereas in a small-scale thunderstorm the motion is
dominantly vertical.

Question 23

Explain how a decrease in vertical shear can lead to the demise of a
thunderstorm.

Answer 23

A decrease in the vertical wind shear would generate a more upright storm, so
the downdraft would fall into the updraft and kill the source of the storm’s energy

Question 24

Explain why a low-level vertical wind shear is important in generating
rotation around the vertical axis in a mesoscale cyclone, and hence to the
possible formation of a tornado.

Answer 24

Low level vertical wind shear generates horizontal vorticity which, when lifted in
the updraft, gets titled into vertical vorticity (horizontal rotation about the vertical
axis). This vertical vorticity can then get stretched by the updraft, and vorticity
stretching increases the rotation rate, which could lead to a tornado.

Question 25

Describe how the sea surface temperature, trade winds, the thermocline,
upwelling and precipitation can change during El Niño versus La Niña.

Answer 25

During La Niña there are warm sea surface temperatures towards the west, which
allows for a strong pressure gradient from east to west and strong easterly trade
winds. This creates upwelling along the eastern Pacific, and a dry climate in the
region, with downwelling and a wetter climate in the west. During El Niño, the
warm surface water spreads across the Pacific, so there is a small pressure
gradient, so weak to no trade winds. This suppresses upwelling along the east
coast, and brings rainfall to the region while the west experiences drier than
normal conditions.

Question 26

How can understanding phenomena like ENSO help with better long term
forecasting?

Answer 26

Climate oscillations have a large impact on global weather patterns, affecting
regional temperature and rainfall patterns. Understanding how different phases of
climate oscillations come about, and how they impact other regions of the globe
can give forecasters a better understanding of the base climatology expected
during a particular climate phase. Understanding the climatology of regions is
important for making more accurate long range forecasts.

Question 27

What impacts would El Niño have on hurricane formation in the Northern
Pacific and Atlantic Ocean?

Answer 27

Fewer hurricanes in the Atlantic, as the westerlies are strengthened,
which increases vertical wind shear and breaks up forming hurricanes. In the
Pacific, warmer waters strengthen hurricane formation

Question 28

What impacts would La Niña have on hurricane formation in the Northern
Pacific and Atlantic Ocean?

Answer 28

La Niña: There are more hurricanes in the Atlantic, as there are weaker westerlies,
so less vertical wind shear which allows more hurricanes to form. In the Pacific,
cooler-than-normal water temperatures suppress hurricane formation.