The original air, in Vancouver (sea level, 0 m) was at 10°C. What is the dew point temperature of this air? (Think – the air is rising and cooling at the DAR [see your notes … the air cools ________°C every 1000m) You know the condensation level/elevation on Mt. Seymour. How many °C did the air cool as it rose that distance from sea level (0 m)? Therefore, what is the dew point temperature of the air? Use this calculation:

        10°C (starting temperature at sea level)

        –    the temperature decrease between 0 m and the condensation/cloud level [use DAR]     ----------------------------

        =   dew point temperature

What is the dew point temperature?

Question

The original air, in Vancouver (sea level, 0 m) was at 10°C.  What is the dew point temperature of this air?  (Think – the air is rising and cooling at the DAR [see your notes … the air cools ________°C every 1000m)  You know the condensation level/elevation on Mt. Seymour.  How many °C did the air cool as it rose that distance from sea level (0 m)?  Therefore, what is the dew point temperature of the air?  Use this calculation:

10°C (starting temperature at sea level)

–    the temperature decrease between 0 m and the condensation/cloud level [use DAR]     ----------------------------

=   dew point temperature

What is the dew point temperature?

BlackTom AI · Accepted Answer

We start by laying out what the question is asking: determine the dew point temperature of the air that originates at 10°C at sea level (0 m) in Vancouver, given that it rises and cools at the dry adiabatic lapse rate (DAR) until reaching the condensation level on Mt. Seymour. The key idea is that the dew point is the temperature at which the rising air becomes saturated and condensation begins; this occurs when the actual air temperature has cooled to the dew point.

Option 1: 10°C. This would imply no cooling occurred between sea level and the condensation level, which contradicts the basic premise that the air is rising and cooling. Since rising air always cools (by about 9.8°C per kilometer under DAR), a final dew point of 10°C would mean the temperature at condensation is still 10°C, which isn’t consistent with the cooling process. Therefore this is incorrect.

Option 2: 15°C. If the dew point were 15°C, the air would need to reach 15°C to become saturated. However, starting at 10°C and cooling as it rises cannot produce a dew point higher than the starting temperature; cooling lowers the temperature, so reaching 15°C as a dew point is impossible in this scenario. This makes this option incorrect.

Option 3: 0°C. A dew point of 0°C means the air has cooled from 10°C down by about 10°C as it ascends to the condensation level estimated by DAR. Since the dry adiabatic lapse rate is roughly 9.8°C per kilometer, the air would drop from 10°C to about 0°C over roughly 1 kilometer of ascent, bringing the temperature down to near 0°C where saturation (dew point) can occur and condensation begins. Given the problem’s cue to use DAR and the typical cloud base height, this outcome is consistent with the expected cooling and the stated calculation, so this option aligns with the physics.

Option 4: 20°C. A dew point of 20°C would require the air to warm or maintain a higher temperature than its initial 10°C as it rises, which is incompatible with the cooling process described by the DAR during ascent. Therefore this cannot be correct.

Option 5: 5°C. While 5°C is closer to the expected cooling, it would imply a drop of only 5°C from the starting 10°C, which corresponds to about half a kilometer of ascent under DAR. If the condensation level is higher than that, the dew point would be lower (closer to 0°C or below). Without evidence of such a shallow ascent, this option is less consistent with the stated use of DAR to reach the condensation level, making it unlikely in this framing.

Option 6: -10°C. A dew point of -10°C would require the air to cool by 20°C from 10°C, more cooling than the typical DAR drop for a realistic ascent to condensation. This would place the condensation level far higher than plausible for Mt. Seymour in this context and is not supported by the given setup. Hence this is incorrect.

In summary, considering the air rising and cooling via the dry adiabatic lapse rate until reaching condensation, the dew point temperature that matches the described process is 0°C. The other options fail to satisfy the cooling behavior dictated by the DAR, the relation between dew point and saturation, or the physical limits of the scenario.

类似问题

To which meteorological condition does the term “dew point” refer?

Based on the data in Figure 6, there ____ above the surface where air is saturated (remember: air is saturated when temperature and dew point lines overlap).

Air must be cooled to the _____ in order for it to become saturated.

Consider a situation where the air temperature increases but there is no addition or removal of water vapor to the atmosphere. As a result, the dew point will _____.

A parcel of air is saturated. Its dewpoint temperature is equal to its temperature.

Which of the following dew points is least likely to be found in the United States?

If dew points decrease, then...

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