Weather Homework Practice
| # | Answer |
|---|---|
| 1 | Weather is the short-term state of the atmosphere at a specific place and time. Four common variables are temperature, atmospheric pressure, humidity, and wind speed/direction. |
| 2 | Weather refers to short-term atmospheric conditions, while climate describes the long-term average pattern of weather in a region over many years. |
| 3 | Nitrogen is about 78% and oxygen is about 21% of the atmosphere. |
| 4 | Water vapor is important because it is a major greenhouse gas, participates in condensation and cloud formation, and influences humidity, precipitation, and energy transfer in the atmosphere. |
| 5 | Relative humidity is the percentage of water vapor present in air compared with the maximum amount the air can hold at that temperature. |
| 6 | Warm air has greater molecular kinetic energy, which increases the equilibrium vapor pressure of water and allows more water molecules to remain in the gas phase before condensation occurs. |
| 7 | The dew point is the temperature at which air becomes saturated with water vapor and condensation begins. |
| 8 | At night, surfaces lose heat by radiation and cool the nearby air. If the air temperature drops to the dew point, water vapor condenses on the cooler grass surface. |
| 9 | A cloud is made of tiny liquid water droplets, ice crystals, or both, suspended in air. |
| 10 | Condensation nuclei are small particles such as dust, sea salt, or aerosols that provide surfaces on which water vapor can condense. They are necessary because condensation occurs more easily on particles than by spontaneous droplet formation in clean air. |
| 11 | Gas to liquid; this phase change is called condensation. |
| 12 | Adiabatic expansion causes rising air to cool because the air pressure decreases with altitude, allowing the air parcel to expand and do work on its surroundings. |
| 13 | As moist air rises on the windward side, it cools and loses water by precipitation. The descending air on the leeward side warms by compression and is drier, creating a rain shadow effect. |
| 14 | H2O. |
| 15 | An aerosol is a suspension of tiny solid particles or liquid droplets in a gas, such as smoke, dust, sulfate particles, or sea spray in the atmosphere. |
| 16 | Aerosols can act as cloud condensation nuclei, influence cloud droplet size, modify cloud brightness and lifetime, and affect precipitation patterns. |
| 17 | Oceans have a high heat capacity, so they absorb and release heat slowly, moderating temperature changes in nearby coastal areas. |
| 18 | Evaporation absorbs latent heat from the surroundings, cooling the environment, while condensation releases latent heat to the surroundings, warming the air and helping power storms. |
| 19 | Evaporation adds water vapor to the atmosphere, and condensation converts that vapor back into liquid droplets or ice crystals, leading to clouds, precipitation, and recycling of water. |
| 20 | Atmospheric pressure is lower at high altitude because there is less air above a given point, so the weight of the air column pressing down is smaller. |
| 21 | Molar mass of H2O = 18.0 g/mol. Mass = 2.50 mol × 18.0 g/mol = 45.0 g. |
| 22 | Moles = mass ÷ molar mass = 36.0 g ÷ 18.0 g/mol = 2.00 mol. |
| 23 | Number of molecules = 0.40 mol × 6.022 × 10^23 molecules/mol = 2.4 × 10^23 molecules. |
| 24 | Carbon dioxide is a molecular compound named carbon dioxide. It is relevant because it is a greenhouse gas that absorbs infrared radiation and influences atmospheric temperature and climate-related weather patterns. |
| 25 | The greenhouse effect is the warming of Earth’s surface and lower atmosphere because gases such as water vapor, carbon dioxide, and methane absorb and re-emit infrared radiation. This helps trap heat near the surface. |
| 26 | Water vapor is abundant, changes phase easily, releases or absorbs large amounts of latent heat, and strongly affects cloud formation, precipitation, and energy transfer. |
| 27 | H2O(g) → H2O(l) |
| 28 | Saturation means air contains the maximum amount of water vapor possible at a given temperature. Supersaturation means the air contains more water vapor than the saturation amount, often requiring special conditions and leading to condensation. |
| 29 | As temperature increases, the equilibrium vapor pressure of water increases because more molecules have enough energy to escape into the gas phase. |
| 30 | Relative humidity decreases because warmer air has a higher saturation vapor capacity, so the same amount of water vapor represents a smaller fraction of the maximum possible amount. |
| 31 | Fog forms when air near the ground cools to its dew point, causing water vapor to condense into tiny suspended droplets close to the surface. |
| 32 | Fog is a cloud at ground level, while a cloud forms higher in the atmosphere. |
| 33 | Precipitation is water released from clouds that falls to Earth as rain, snow, sleet, or hail. |
| 34 | Cloud droplets are initially too small and light to fall quickly. They must grow by collision-coalescence or the ice-crystal process until gravity overcomes air resistance. |
| 35 | Acid rain primarily contains sulfuric acid (H2SO4) and nitric acid (HNO3) dissolved in rainwater, though it may also contain other acidic species. |
| 36 | A simplified pathway is SO2 + H2O + 1/2 O2 → H2SO4. |
| 37 | 4 NO2 + 2 H2O + O2 → 4 HNO3 |
| 38 | They react in the atmosphere to form strong acids such as sulfuric acid and nitric acid, which lower the pH of precipitation. |
| 39 | pH is a measure of hydrogen ion concentration. Acid rain has a lower pH than normal rainwater because it contains more dissolved acid. |
| 40 | A pH of 4.0 is significantly lower than 5.6, meaning the hydrogen ion concentration is much higher. This indicates extra acidic pollutants are present beyond natural carbonic acid levels. |
| 41 | [H+] = 10^-pH = 10^-4.0 = 1.0 × 10^-4 M. |
| 42 | pH = -log(3.2 × 10^-5) ≈ 4.49. |
| 43 | Particulate matter scatters and absorbs light, reducing visibility and making the air appear hazy or smoggy. |
| 44 | Smog is polluted air containing a mixture of smoke, ozone, nitrogen oxides, volatile organic compounds, and particulates. It forms through atmospheric chemical reactions, especially in sunlight. |
| 45 | Stratospheric ozone protects life by absorbing UV radiation, but ground-level ozone is a reactive oxidant that harms respiratory health and plants and contributes to smog. |
| 46 | Sunlight can photolyze nitrogen dioxide: NO2 + hν → NO + O. The oxygen atom then reacts with O2 to form ozone: O + O2 → O3. |
| 47 | Thunderstorms involve condensation and freezing processes that release latent heat, which fuels strong updrafts and helps intensify convection. |
| 48 | The high temperature of lightning breaks the strong N≡N and O=O bonds in air, allowing nitrogen and oxygen to react and form NO and NO2, which can later form nitric acid. |
| 49 | It indicates that the balloon has risen to a higher altitude where there is less air above it, so the weight of the overlying air column is smaller. |
| 50 | Phase changes of water control cloud formation and release or absorption of latent heat, which affects atmospheric stability and storm intensity. Atmospheric gases such as water vapor, carbon dioxide, and ozone influence radiation balance and temperature. Aerosols provide condensation nuclei that help droplets form and can alter cloud properties and precipitation efficiency. Together, these factors shape clouds, storms, visibility, and rainfall patterns. |