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April 16, 2012

Weather Education Episode #7: Understanding Skew-T

RedOrbit Meteorologist Joshua Kelly

In this lesson we are going to look at understanding the basics to a Skew-T and how we use them in weather to help prepare our weather forecast and also use them for forecasting severe weather.

Block #1 MB Level: This is a scale to show us how high off the ground each reading is on our skew-t. Most upper balloon reports make it to a least 200mb or higher, which is around 30,000ft.

Block#2 Temperatures:
This is a horizontal line that extends from the bottom left to the bottom right showing us the temperatures of the sounding from various heights.

Block#3 Saturation Mixing Ratio Lines: These are the dashed lines you see from lower left extending to the upper right of the skew-t. These lines can help us determine the saturation of an air parcel as it rises from the ground to the upper atmosphere.

Block#4 Dry Adiabats Lines: These extend from the lower left to the upper right and are solid lines, they help us determine how dry a parcel could be if it rises with height.

Block#5 Moist Adiabats lines: These lines help us to determine how moist a parcel can be as it rises up in the atmosphere.

Block #6 Winds/Height: This is the line on the far right of the skew-t that shows the wind barbs with height. We here can determine how strong the winds are with height. In the example above we have Northwest winds at 25kts at about 5,000ft.

Block#7 Actual Sounding Temp: This is the blue line that extends from the surface upwards.  It is showing us the actual air temperatures with height. We can use this to determine many factors of our forecast from high temperatures to how cold it will get in the evening and also if we are going to see clouds form or not.

Block#8 Actual Sounding Dew-point: This is the red line that extends from the bottom to the top showing us how moist the air is actually outside. We can also use this to determine where the clouds are going to form and if the air is dry or moist.

The information above is just very basic information about a Skew-T. If you were to go to college you would be taking this information and learning a lot more about it.

Here are a few examples to go over for this lesson to see how much you understand.  First, if we look at the temperature at the surface, what would it be? About 22-23C. If we look at the dew-point at the surface we see that it is about 15-17C. By knowing this we now know that the air on the ground is not saturated and there are no clouds on the ground such as Fog. If we follow both the blue and red line upwards when we get to around 3,000ft we see that they get closer together to each other. This tells the meteorologist that there may be a possibility of clouds at this level.

That concludes this weather lesson, hope you enjoyed.