ERTH
430:Fluid Dynamic in Earth Systems |
In-Class Exercise:(for class Friday, Oct. 6)Temperature Changes at a Location |
Dr. Dave Dempsey Dept. of Earth & Climate Sciences SFSU, Fall 2017 |

- You are standing outside. With a thermometer, you observe the air temperature to be falling.
You feel a breeze blowing, and you happen to know that the air is coming from a location nearby where the temperature is colder than where you are.

- Suppose that air parcels are conserving their temperature in this situation. How might you account for your observation that the temperature is falling,
assuming that your observation is accurate?

- What factors might affect the
*rate*at which you observe the temperature to be falling? [*Hint*: I have in mind three, relatively intuitive factors.] How might mechanism causing the temperature to change where you are standing depend on these factors mathematically?

- What kind of time derivative are you observing?

- Write down an equation for the rate of change of temperature in your situation.

- Explain why the mechanism that you identify in (a) above is meaningless in the context of a conservation equation.

- Suppose that air parcels are conserving their temperature in this situation. How might you account for your observation that the temperature is falling,
assuming that your observation is accurate?
- On another day, you are again standing outside. With a thermometer, you observe the air temperature to be falling.
You feel a breeze blowing, and you happen to know that the air is coming from a location nearby where the temperature is warmer than where you are.

- How might you account for your observation that the temperature is falling,
assuming that your observation is accurate?

- How might you account for your observation that the temperature is falling,
assuming that your observation is accurate?
- Based on your result in (1)(d) above, briefly explain how, in principle, you might use your equation to make a
forecast at a particular location.

- How much, if any, of the foregoing might apply to fluid velocity (instead of temperature) at a location? What, if anything, would you have to change?