When working out the numerical problems, make sure you use a consistent set of units.

1. It has been empirically esablished that the growth rate of deposition nuclei can be expressed as:

Where S_i = the supersaturation percentage of air (i.e. 101) and b and a are constants. N_D is the number of ice nuclei per cubic meter. Experimentally b = 0.13 and a ranges from 3 to 8.

From this empirical relationship, specify the combinations of S_i and a that are required to produce N_D = 100 and 10,000,000 respectively. Also provide a graphical representation of your solutions

2. Calculate the times taken for water drops of radii 1, 10 and 100 microns to fall a distance of 1 km in air at terminal velocity. Take the air viscosity to be 2 x10^-5 kg m^-1 s^-1 In the case of the largest droplet (where you should find a fall time of 10 minutes) comment on why this calculation is incorrect.



3. Suppose that Mt. St Helens blows and that ash particles are blown to a height in the stratosphere where the pressure = 50 mb. Assume the tropsphere starts at a pressure of 200 mb. The ash particles are spherical with a mean radius of 0.1 microns and a density of 2600 kg m^-3, Estimate the time it takes for these particles to reach the earth's surface.



4. Get the data table from The Official El Nino Monitoring Site . The data consist of 3 month averaged index values for each month of the year going back to 1950.

Using any data analysis tools that you want, try and identify if there is a characteristic time scale associated with the appearance of el nino events (those are the ones with red numbers). In addition, on a per decade basis, determine the number of strong El NIno months, where strong means values greater than or equal to 0.9



5. The Eugene Rainfall Anamoly:

• Download the daily rainfall data for Eugene
• Download the daily rainfall data for Salem

• Produce a smoothed wave form of the annual precipitation for both Salem and Eugene from 1950 to now and comment on any differences between these wave forms.
• Correlate the Eugene and Salem monthly totals and comment on any anamolies that you notice.
• Compare the winter time precipitation at both sites where Winter is defined as the 4 consecutive months of November, December, January and February over the time internal 2000 to now and 1950 - 2000 and comment on any trends you might see.

6. HINT: