1f. Vertical Profiles of MoistureIn Chapter 3, you saw how
simplified thermodynamic diagrams can be used to plot the vertical
profile of temperature. Because dew point values are likewise expressed
as temperatures, they, too, can be plotted on thermodynamic charts. In
fact, by plotting temperatures and dew points simultaneously, you can
obtain considerable information about cloud conditions. Refer to the
profiles (also called soundings) of temperature and dew point shown in
the Stuve diagram (explained in Chapter 3) in Figure 5-3-1, taken from
Stapleton Airport, near Denver, Colorado, at midnight, Greenwich mean
time, on April 12,2002.Reading a Thermodynamic DiagramThe example in
Figure 5-3-1 can first be used to illustrate how plots of temperature
(the curve on the right) and dew point (left) can give us information
about cloud cover. The temperature at the surface is 17 °C (63 °F), and
the dew point is −4 °C (25 °F). Given the disparity between the
temperature and dew point, we know that the surface relative humidity is
low. But this changes at about the 560 mb level (at a height of about
4850 m, or 15,900 ft, above the surface), where the two values become
nearly equal to each other. At this level the air is saturated and we
have the base of a cloud deck (a slight measurement error accounts for
the plotted temperature and dew point values not being exactly equal).
The air remains saturated up to about the 460 mb level, where the cloud
tops out. Because the air is saturated in the layer of air between 4850
and 6500 m above the surface, we can infer that the cloud is about 1650
(5400 ft) m thick.Mixing Ratios on a Thermodynamic DiagramThe
thermodynamic diagram shown here is slightly more complex than the one
in Chapter 3, because it includes an additional set of lines that
provides one more type of moisture information. The dashed red lines
that slope gently to the left as they extend upward can be used to
estimate the mixing ratio and the saturation mixing ratio at any level.
To determine the mixing ratio at any level, you observe the position of
the dew point plot and interpolate between the dashed red lines. Let’s
first see how the plot of the air temperature profile can be used to
determine the saturation mixing ratio at a given pressure level, in this
case the 700 mb level, At that level the dew point is barely greater
than −10 °C (14 °F). Notice that the point on the graph where the dew
point profile crosses the 700 mb level occurs right between the two
sloping lines labeled 2 and 4. That indicates that actual mixing ratio
at the 700 mb level is right between 2 (g/kg) air and 4 (g/kg)– with 3
g/kg a very good approximation.We can follow a similar procedure to find
out what the saturation mixing ratio is at the 700 mb level. At the 700
mb level the air temperature is 2 °C (35.6 °F). The point of
intersection for the temperature profile falls right on the mixing ratio
line labeled as 7. Thus, the air at the 700 mb level has a saturation
mixing ratio of just under 7 grams of water vapor per kilogram of dry
air.To determine the relative humidity at the 700 mb level we can use
the values just, obtained to get,...This procedure can be performed at
the surface or any other level of the atmosphere.Thermodynamic Diagrams
and ForecastingLater in this chapter, we will see how ther modynamic
diagrams can give us information in forecasting the likelihood of cloud
development.What index of moisture content is directly plotted on
thermodynamic diagrams?FIGURE 5-3-1 A Sounding of Temperature and Dew
Point. This chart plots temperature and dew points throughout the
troposphere and much of the stratosphere. The slightly sloping red lines
depict values of mixing ratio in grams of water vapor per kilogram of
dry air (labeled just above the x-axis). Meteorologists use these lines
along with the plots of temperature to determine the saturation mixing
ratio; these lines and the dew point profiles are used to obtain the
actual mixing ratio.... Get solution
2f. Vertical Profiles of MoistureIn Chapter 3, you saw how simplified thermodynamic diagrams can be used to plot the vertical profile of temperature. Because dew point values are likewise expressed as temperatures, they, too, can be plotted on thermodynamic charts. In fact, by plotting temperatures and dew points simultaneously, you can obtain considerable information about cloud conditions. Refer to the profiles (also called soundings) of temperature and dew point shown in the Stuve diagram (explained in Chapter 3) in Figure 5-3-1, taken from Stapleton Airport, near Denver, Colorado, at midnight, Greenwich mean time, on April 12,2002.Reading a Thermodynamic DiagramThe example in Figure 5-3-1 can first be used to illustrate how plots of temperature (the curve on the right) and dew point (left) can give us information about cloud cover. The temperature at the surface is 17 °C (63 °F), and the dew point is −4 °C (25 °F). Given the disparity between the temperature and dew point, we know that the surface relative humidity is low. But this changes at about the 560 mb level (at a height of about 4850 m, or 15,900 ft, above the surface), where the two values become nearly equal to each other. At this level the air is saturated and we have the base of a cloud deck (a slight measurement error accounts for the plotted temperature and dew point values not being exactly equal). The air remains saturated up to about the 460 mb level, where the cloud tops out. Because the air is saturated in the layer of air between 4850 and 6500 m above the surface, we can infer that the cloud is about 1650 (5400 ft) m thick.Mixing Ratios on a Thermodynamic DiagramThe thermodynamic diagram shown here is slightly more complex than the one in Chapter 3, because it includes an additional set of lines that provides one more type of moisture information. The dashed red lines that slope gently to the left as they extend upward can be used to estimate the mixing ratio and the saturation mixing ratio at any level. To determine the mixing ratio at any level, you observe the position of the dew point plot and interpolate between the dashed red lines. Let’s first see how the plot of the air temperature profile can be used to determine the saturation mixing ratio at a given pressure level, in this case the 700 mb level, At that level the dew point is barely greater than −10 °C (14 °F). Notice that the point on the graph where the dew point profile crosses the 700 mb level occurs right between the two sloping lines labeled 2 and 4. That indicates that actual mixing ratio at the 700 mb level is right between 2 (g/kg) air and 4 (g/kg)– with 3 g/kg a very good approximation.We can follow a similar procedure to find out what the saturation mixing ratio is at the 700 mb level. At the 700 mb level the air temperature is 2 °C (35.6 °F). The point of intersection for the temperature profile falls right on the mixing ratio line labeled as 7. Thus, the air at the 700 mb level has a saturation mixing ratio of just under 7 grams of water vapor per kilogram of dry air.To determine the relative humidity at the 700 mb level we can use the values just, obtained to get,...This procedure can be performed at the surface or any other level of the atmosphere.Thermodynamic Diagrams and ForecastingLater in this chapter, we will see how ther modynamic diagrams can give us information in forecasting the likelihood of cloud development.How can we estimate the mixing ratio from a thermodynamic diagram?FIGURE 5-3-1 A Sounding of Temperature and Dew Point. This chart plots temperature and dew points throughout the troposphere and much of the stratosphere. The slightly sloping red lines depict values of mixing ratio in grams of water vapor per kilogram of dry air (labeled just above the x-axis). Meteorologists use these lines along with the plots of temperature to determine the saturation mixing ratio; these lines and the dew point profiles are used to obtain the actual mixing ratio.... Get solution
2f. Vertical Profiles of MoistureIn Chapter 3, you saw how simplified thermodynamic diagrams can be used to plot the vertical profile of temperature. Because dew point values are likewise expressed as temperatures, they, too, can be plotted on thermodynamic charts. In fact, by plotting temperatures and dew points simultaneously, you can obtain considerable information about cloud conditions. Refer to the profiles (also called soundings) of temperature and dew point shown in the Stuve diagram (explained in Chapter 3) in Figure 5-3-1, taken from Stapleton Airport, near Denver, Colorado, at midnight, Greenwich mean time, on April 12,2002.Reading a Thermodynamic DiagramThe example in Figure 5-3-1 can first be used to illustrate how plots of temperature (the curve on the right) and dew point (left) can give us information about cloud cover. The temperature at the surface is 17 °C (63 °F), and the dew point is −4 °C (25 °F). Given the disparity between the temperature and dew point, we know that the surface relative humidity is low. But this changes at about the 560 mb level (at a height of about 4850 m, or 15,900 ft, above the surface), where the two values become nearly equal to each other. At this level the air is saturated and we have the base of a cloud deck (a slight measurement error accounts for the plotted temperature and dew point values not being exactly equal). The air remains saturated up to about the 460 mb level, where the cloud tops out. Because the air is saturated in the layer of air between 4850 and 6500 m above the surface, we can infer that the cloud is about 1650 (5400 ft) m thick.Mixing Ratios on a Thermodynamic DiagramThe thermodynamic diagram shown here is slightly more complex than the one in Chapter 3, because it includes an additional set of lines that provides one more type of moisture information. The dashed red lines that slope gently to the left as they extend upward can be used to estimate the mixing ratio and the saturation mixing ratio at any level. To determine the mixing ratio at any level, you observe the position of the dew point plot and interpolate between the dashed red lines. Let’s first see how the plot of the air temperature profile can be used to determine the saturation mixing ratio at a given pressure level, in this case the 700 mb level, At that level the dew point is barely greater than −10 °C (14 °F). Notice that the point on the graph where the dew point profile crosses the 700 mb level occurs right between the two sloping lines labeled 2 and 4. That indicates that actual mixing ratio at the 700 mb level is right between 2 (g/kg) air and 4 (g/kg)– with 3 g/kg a very good approximation.We can follow a similar procedure to find out what the saturation mixing ratio is at the 700 mb level. At the 700 mb level the air temperature is 2 °C (35.6 °F). The point of intersection for the temperature profile falls right on the mixing ratio line labeled as 7. Thus, the air at the 700 mb level has a saturation mixing ratio of just under 7 grams of water vapor per kilogram of dry air.To determine the relative humidity at the 700 mb level we can use the values just, obtained to get,...This procedure can be performed at the surface or any other level of the atmosphere.Thermodynamic Diagrams and ForecastingLater in this chapter, we will see how ther modynamic diagrams can give us information in forecasting the likelihood of cloud development.How can we estimate the mixing ratio from a thermodynamic diagram?FIGURE 5-3-1 A Sounding of Temperature and Dew Point. This chart plots temperature and dew points throughout the troposphere and much of the stratosphere. The slightly sloping red lines depict values of mixing ratio in grams of water vapor per kilogram of dry air (labeled just above the x-axis). Meteorologists use these lines along with the plots of temperature to determine the saturation mixing ratio; these lines and the dew point profiles are used to obtain the actual mixing ratio.... Get solution
