Question
omestic animals have local and integrated mechanisms to ensure that the
Assignment2
From the data given above, help the farmer estimate the daily reference
evapotranspiration(ETo)using
b)What mechanisms have some organisms developed to regulate and compensate
NB: The effect of Soil heat flux is negligible
temperature changes?
data for 15thApril, 2024from a meterological station near his farm as shown in the table
Daily maximum air temperature, Tmax29 °C
Actual recorded Sunshine hours, n8.5 hours
(i)The blaney-criddle method
A Ricefarmer from lusaka, 15.5 °S and 28.5 °E obtained the following meteorological
below:
Daily minimum air temperature, Tmin18 °C
Elevation above sea level, Z1800m
a)With the aid of a diagram, show the temperature dependent zone of survival for
temperature of the body is maintained at constant ideal levels.
Mean relative humidity, RH50%
Average wind speed at 2m, U23 ms-1
PARAMETER
living organisms.
(ii)The penman-monteith method
Assignment2
From the data given above, help the farmer estimate the daily reference
evapotranspiration(ETo)using
b)What mechanisms have some organisms developed to regulate and compensate
NB: The effect of Soil heat flux is negligible
temperature changes?
data for 15thApril, 2024from a meterological station near his farm as shown in the table
Daily maximum air temperature, Tmax29 °C
Actual recorded Sunshine hours, n8.5 hours
(i)The blaney-criddle method
A Ricefarmer from lusaka, 15.5 °S and 28.5 °E obtained the following meteorological
below:
Daily minimum air temperature, Tmin18 °C
Elevation above sea level, Z1800m
a)With the aid of a diagram, show the temperature dependent zone of survival for
temperature of the body is maintained at constant ideal levels.
Mean relative humidity, RH50%
Average wind speed at 2m, U23 ms-1
PARAMETER
living organisms.
(ii)The penman-monteith method
Answers
GPT-4o mini
To estimate the daily reference evapotranspiration (ETo) for the given data, we can use two methods: the Blaney-Criddle method and the Penman-Monteith method. Below is a brief explanation of each method along with calculations based on the provided data.
### **a) Blaney-Criddle Method**
The Blaney-Criddle formula for estimating reference evapotranspiration (ETo) is as follows:
\[
ETo = p \times (0.46 \times T + 8)
\]
Where:
- \(ETo\) = reference evapotranspiration (mm/day)
- \(p\) = the mean daily percentage of hours of sunshine
- \(T\) = mean daily temperature (°C)
First, we need to calculate the mean daily temperature (T):
\[
T = \frac{T_{max} + T_{min}}{2} = \frac{29 + 18}{2} = 23.5 \, °C
\]
Next, we will calculate the mean daily percentage of hours of sunshine (p):
\[
p = \frac{n}{24} = \frac{8.5}{24} \approx 0.3542
\]
Now we can substitute these values into the Blaney-Criddle formula:
\[
ETo = 0.3542 \times (0.46 \times 23.5 + 8)
\]
Calculating inside the parentheses:
\[
0.46 \times 23.5 = 10.81
\]
\[
0.46 \times 23.5 + 8 = 10.81 + 8 = 18.81
\]
Now calculating ETo:
\[
ETo = 0.3542 \times 18.81 \approx 6.66 \, mm/day
\]
### **b) Penman-Monteith Method**
The Penman-Monteith equation is more complex and provides a more accurate estimate of ETo. The formula is given by:
\[
ETo = \frac{0.408 \Delta (R_n - G) + \gamma \frac{900}{T + 273} U (e_s - e_a)}{\Delta + \gamma (1 + 0.34 U)}
\]
Where:
- \(\Delta\) = slope of the vapor pressure curve (kPa/°C)
- \(R_n\) = net radiation (MJ/m²/day)
- \(G\) = soil heat flux density (MJ/m²/day, negligible in this case)
- \(\gamma\) = psychrometric constant (kPa/°C)
- \(T\) = air temperature in °C
- \(U\) = wind speed at 2 m height (m/s)
- \(e_s\) = saturation vapor pressure (kPa)
- \(e_a\) = actual vapor pressure (kPa)
1. **Determine Net Radiation \(R_n\):**
- A common estimate, if not provided, is around 15% of the solar radiation. Assuming solar radiation \(R_{sol} = 20.9 \, MJ/m²/day\) (based on 8.5 hours of sunshine), estimate:
\[
R_n = 0.85 \times R_{sol} = 0.85 \times 20.9 \approx 17.7 \, MJ/m²/day
\]
2. **Calculate Slope (\(\Delta\)) and Psychrometric Constant (\(\gamma\)):**
- \(\Delta \approx 0.611 \times e^{(17.27 \times T / (T + 237.3))}\) can be calculated using temperature.
- For typical conditions, use \(\gamma \approx 0.065\) kPa/°C.
3. **Saturation Vapor Pressure (e_s) and Actual Vapor Pressure (e_a):**
- \(e_s\) can be calculated using the formula:
\[
e_s = 6.11 \times e^{(17.27 \times T / (T + 237.3))}
\]
Using \(T = 23.5°C\):
\[
e_s \approx 6.11 \times e^{(17.27 \times 23.5 / (23.5 + 237.3))} \approx 2.8 \, kPa
\]
- Actual vapor pressure \(e_a\) can be derived from the relative humidity:
\[
e_a = e_s \times \frac{RH}{100} \approx 2.8 \times \frac{50}{100} \approx 1.4 \, kPa
\]
4. **Final ETo Calculation:**
By plugging these values into the Penman-Monteith equation, you can estimate ETo.
\[ \Delta = \frac{4098 \times (0.611 \times e^{(17.27 \times T / (T + 237.3))})}{(T + 237.3)^2} \]
This will yield an answer for \(ETo\) that you can interpret accordingly.
### **Temperature Regulation in Organisms**
Many organisms develop several physiological and behavioral adaptations to regulate and compensate for temperature changes, including:
1. **Thermoregulation:**
- Endothermic animals (like mammals) generate heat through metabolic processes to maintain a stable internal temperature.
- Ectothermic animals (like reptiles) rely on external environments, often seeking out heated or shaded areas.
2. **Behavioral Adaptations:**
- Animals may alter their activity patterns, becoming more active during cooler parts of the day (e.g., nocturnal behavior).
- Migration practices in birds and other animals to avoid extreme temperatures.
3. **Physiological Changes:**
- Altering blood flow to extremities to conserve or dissipate heat.
- Developing insulating fur or feathers for cold weather and shedding for warmer temperatures.
4. **Metabolic Adjustments:**
- Some species can enter a state of dormancy or torpor to survive low temperatures or adverse environmental conditions.
### Diagram for Temperature-Dependent Survival Zones
A diagram can represent this concept by showing thermal performance curves in organisms, with temperature on the x-axis and performance (e.g., growth, reproduction) on the y-axis, highlighting the optimal range and stressful temperature zones.
This comprehensive overview addresses both methods for estimating ETo and discusses mechanisms of temperature regulation in organisms.
### **a) Blaney-Criddle Method**
The Blaney-Criddle formula for estimating reference evapotranspiration (ETo) is as follows:
\[
ETo = p \times (0.46 \times T + 8)
\]
Where:
- \(ETo\) = reference evapotranspiration (mm/day)
- \(p\) = the mean daily percentage of hours of sunshine
- \(T\) = mean daily temperature (°C)
First, we need to calculate the mean daily temperature (T):
\[
T = \frac{T_{max} + T_{min}}{2} = \frac{29 + 18}{2} = 23.5 \, °C
\]
Next, we will calculate the mean daily percentage of hours of sunshine (p):
\[
p = \frac{n}{24} = \frac{8.5}{24} \approx 0.3542
\]
Now we can substitute these values into the Blaney-Criddle formula:
\[
ETo = 0.3542 \times (0.46 \times 23.5 + 8)
\]
Calculating inside the parentheses:
\[
0.46 \times 23.5 = 10.81
\]
\[
0.46 \times 23.5 + 8 = 10.81 + 8 = 18.81
\]
Now calculating ETo:
\[
ETo = 0.3542 \times 18.81 \approx 6.66 \, mm/day
\]
### **b) Penman-Monteith Method**
The Penman-Monteith equation is more complex and provides a more accurate estimate of ETo. The formula is given by:
\[
ETo = \frac{0.408 \Delta (R_n - G) + \gamma \frac{900}{T + 273} U (e_s - e_a)}{\Delta + \gamma (1 + 0.34 U)}
\]
Where:
- \(\Delta\) = slope of the vapor pressure curve (kPa/°C)
- \(R_n\) = net radiation (MJ/m²/day)
- \(G\) = soil heat flux density (MJ/m²/day, negligible in this case)
- \(\gamma\) = psychrometric constant (kPa/°C)
- \(T\) = air temperature in °C
- \(U\) = wind speed at 2 m height (m/s)
- \(e_s\) = saturation vapor pressure (kPa)
- \(e_a\) = actual vapor pressure (kPa)
1. **Determine Net Radiation \(R_n\):**
- A common estimate, if not provided, is around 15% of the solar radiation. Assuming solar radiation \(R_{sol} = 20.9 \, MJ/m²/day\) (based on 8.5 hours of sunshine), estimate:
\[
R_n = 0.85 \times R_{sol} = 0.85 \times 20.9 \approx 17.7 \, MJ/m²/day
\]
2. **Calculate Slope (\(\Delta\)) and Psychrometric Constant (\(\gamma\)):**
- \(\Delta \approx 0.611 \times e^{(17.27 \times T / (T + 237.3))}\) can be calculated using temperature.
- For typical conditions, use \(\gamma \approx 0.065\) kPa/°C.
3. **Saturation Vapor Pressure (e_s) and Actual Vapor Pressure (e_a):**
- \(e_s\) can be calculated using the formula:
\[
e_s = 6.11 \times e^{(17.27 \times T / (T + 237.3))}
\]
Using \(T = 23.5°C\):
\[
e_s \approx 6.11 \times e^{(17.27 \times 23.5 / (23.5 + 237.3))} \approx 2.8 \, kPa
\]
- Actual vapor pressure \(e_a\) can be derived from the relative humidity:
\[
e_a = e_s \times \frac{RH}{100} \approx 2.8 \times \frac{50}{100} \approx 1.4 \, kPa
\]
4. **Final ETo Calculation:**
By plugging these values into the Penman-Monteith equation, you can estimate ETo.
\[ \Delta = \frac{4098 \times (0.611 \times e^{(17.27 \times T / (T + 237.3))})}{(T + 237.3)^2} \]
This will yield an answer for \(ETo\) that you can interpret accordingly.
### **Temperature Regulation in Organisms**
Many organisms develop several physiological and behavioral adaptations to regulate and compensate for temperature changes, including:
1. **Thermoregulation:**
- Endothermic animals (like mammals) generate heat through metabolic processes to maintain a stable internal temperature.
- Ectothermic animals (like reptiles) rely on external environments, often seeking out heated or shaded areas.
2. **Behavioral Adaptations:**
- Animals may alter their activity patterns, becoming more active during cooler parts of the day (e.g., nocturnal behavior).
- Migration practices in birds and other animals to avoid extreme temperatures.
3. **Physiological Changes:**
- Altering blood flow to extremities to conserve or dissipate heat.
- Developing insulating fur or feathers for cold weather and shedding for warmer temperatures.
4. **Metabolic Adjustments:**
- Some species can enter a state of dormancy or torpor to survive low temperatures or adverse environmental conditions.
### Diagram for Temperature-Dependent Survival Zones
A diagram can represent this concept by showing thermal performance curves in organisms, with temperature on the x-axis and performance (e.g., growth, reproduction) on the y-axis, highlighting the optimal range and stressful temperature zones.
This comprehensive overview addresses both methods for estimating ETo and discusses mechanisms of temperature regulation in organisms.