Which of these ecosystems has the highest net primary productivity per square meter annually?

A) boreal forest
B) open ocean
C) temperate forest
D) savanna
E) tropical rainforest

A car is moving at a constant $19.3 \mathrm{~m} / \mathrm{s}$, and rain is falling at $8.90 \mathrm{~m} / \mathrm{s}$ straight down. What angle $\theta$ (in degrees) does the rain make with respect to the horizontal as observed by the driver?

If forests serve as important sinks for greenhouse gases, describe how past ice ages might have affected the concentration levels of carbon dioxide in the atmosphere.

The acidity of a solution is measured by its $\mathrm{pH}$, with lower $\mathrm{pH}$ values indicating more acidity. A study of acid rain was undertaken in Colorado between 1975 and 1978 , in which the acidity of rain was measured for 150 consecutive weeks. The data followed a generally linear pattern and the regression line was determined to be

$$P=5.43-0.0053 t,$$

where $P$ is the $\mathrm{pH}$ of the rain and $t$ is the number of weeks into the study. Is the $\mathrm{pH}$ level increasing or decreasing over the period of the study? What does this tell you about the level of acidity in the rain?

Explain why the following statement is incorrect:

The probability of rain tomorrow is 120%.

Soybeans are grown for
a. oil.
b. hay.
c. rain.
d. all of the above.

Provide an explanation (including a chemical equation) for why rain is naturally acidic.

Solve the problem.

Suppose that vector $\mathbf{R}$ models the amount of rainfall in inches and the direction it falls, and vector $\mathbf{A}$ models the area in square inches and orientation of the opening of a rain gauge. The total volume $V$ of water collected in the rain gauge is given by $V=|\mathbf{R} \cdot \mathbf{A}|$. This formula calculates the volume of water collected even if the wind is blowing the rain in a slanted direction or the rain gauge is not exactly vertical. Let $\mathbf{R}=\mathbf{i}-2 \mathbf{j}$ and $\mathbf{A}=.5 \mathbf{i}+\mathbf{j}$.

($c$) For the rain gauge to collect the maximum amount of water, what should be true about vectors $\mathbf{R}$ and $\mathbf{A}$ ?

After a heavy rain, the huge drainpipe was a _______ for millions of gallons of water. (conduit)

How can you account for the fact that normal rain is slightly acidic?

A summer rain could begin as a snowstorm in the clouds overhead. How is this possible?

Which of the following types of ecosystem typically has the highest net primary productivity?

a. temperate forest
b. tropical dry forest
c. tropical grassland
d. tropical wet forest

Why is nutrient availability in a tropical rain forest particularly vulnerable to logging?

For each of the following categories, state one action that will help reduce the impacts of climate change: (a) transportation (b) energy production (e) energy conservation (d) forests