ay16-CDeMeo

We can use a model of a parcel of air at some distance r above earth's surface to determine different characteristics of the atmosphere including how density changes at different r values, and how gravitational acceleration changes at different r values. We can assume that the earth's atmosphere is comprised of an ideal gas which allows us to use the ideal gas law: $P=n \times k_B \times T$ n is the number density of particles (in $cm^3$) $k= 1.4 \times 10^{-16} erg K^{-1}$ which is the Bolzmann constant.  a) Think of a small cylindrical parcel of gas, with the axis running vertically in the Earth's atmosphere. The parcel sits a distance r from the Earth's center, and the parcel's size is defined by a height $ \delta r $ is much less than r and a circular cross sectional area A. The parcel will feel pressure pushing up from gas below $P_{up} = P(r)$ and down from above $P_{down} = P(r+ \delta r)$ where pressure is expressed as a function of r. Draw a picture to desc...

      Introduction      To measure the distance between the earth and the sun (the AU), we used a heliostat to determine the angular size of the sun using the heliostat, measure the rotational speed of the sun using the spectrograph, and measure the rotational period of the sun using analysis of sunspots. The rotational speed ($v_{rot}$) and rotational period (P) will allow us to calculate the radius (R) of the sun using the equation $v_{rot}= \frac{2 \pi R}{P}$. Then, we can use triangle geometry to solve for the distance between the sun and the earth as shown in Figure 1. Figure 1 : Solving for distance between the earth and the sun given the radius of the sun and the angular diameter of the sun. Methods Angular Diameter : A heliostat was used to measure how long it takes for the sun to move a length of its own diameter. A heliostat is a series of mirrors that reflects the light of the sun into the lab classroom and onto a table ( Figure 2 ). Once lined u...