diff --git a/esbo_etc/classes/esbo_etc.py b/esbo_etc/classes/esbo_etc.py
index 296488f..1d247a9 100644
--- a/esbo_etc/classes/esbo_etc.py
+++ b/esbo_etc/classes/esbo_etc.py
@@ -1,5 +1,6 @@
 import esbo_etc as eetc
 from esbo_etc.lib.logger import logger
+from esbo_etc.lib.cache import cache
 import logging as log
 import astropy.units as u
 
@@ -65,4 +66,5 @@ class esbo_etc:
             res = detector.getSNR(self.conf.common.exposure_time())
         elif hasattr(self.conf.common, "snr"):
             res = detector.getExpTime(self.conf.common.snr())
+        cache.close()
         return res
diff --git a/esbo_etc/classes/optical_component/Atmosphere.py b/esbo_etc/classes/optical_component/Atmosphere.py
index c3f7b27..23699cc 100644
--- a/esbo_etc/classes/optical_component/Atmosphere.py
+++ b/esbo_etc/classes/optical_component/Atmosphere.py
@@ -3,9 +3,11 @@ from ..IRadiant import IRadiant
 from ..SpectralQty import SpectralQty
 from ..Entry import Entry
 from ...lib.logger import logger
+from ...lib.cache import cache
 import astropy.units as u
 from astropy.io import ascii
 from astropy.modeling.models import BlackBody
+from astropy.table import QTable
 from typing import Union
 import re
 import requests as req
@@ -58,7 +60,8 @@ class Atmosphere(AOpticalComponent):
 
         args = dict()
         if "atran" in kwargs:
-            args = self._fromATRAN(**{x: kwargs[x] for x in kwargs.keys() if x not in ["emission", "temp"]})
+            data = self.__parse_ATRAN(kwargs["atran"])
+            args = self._fromATRAN(parent=kwargs["parent"], atran=data)
         elif "altitude" in kwargs:
             logger.info("Requesting ATRAN transmission profile.")
             data = self.__call_ATRAN(**{x: kwargs[x] for x in kwargs.keys() if x not in ["parent", "temp"]})
@@ -103,7 +106,7 @@ class Atmosphere(AOpticalComponent):
                                              qty_unit_default=u.dimensionless_unscaled)
         return {"parent": parent, "transmittance": transmittance}
 
-    def _fromATRAN(self, parent: IRadiant, atran: str):
+    def _fromATRAN(self, parent: IRadiant, atran: QTable):
         """
         Initialize a new atmosphere model from an ATRAN output file
 
@@ -111,22 +114,21 @@ class Atmosphere(AOpticalComponent):
         ----------
         parent : IRadiant
             The parent element of the atmosphere from which the electromagnetic radiation is received.
-        atran : str
-            Path to the ATRAN output file containing the spectral transmittance-coefficients of the atmosphere.
+        atran : QTable
+            QTable containing the atmospheric transmission coefficients.
 
         Returns
         -------
         args : dict
             The arguments for the class instantiation.
         """
-        # Read the file
-        data = self.__parse_ATRAN(atran)
         # Create spectral quantity
-        transmittance = SpectralQty(data["col2"].quantity, data["col3"].quantity)
+        transmittance = SpectralQty(atran["col2"].quantity, atran["col3"].quantity)
         return {"parent": parent, "transmittance": transmittance}
 
     @u.quantity_input(altitude="length", latitude="angle", water_vapor="length", zenith_angle="angle", wl_min="length",
                       wl_max="length")
+    @cache
     def __call_ATRAN(self, altitude: u.Quantity, wl_min: u.Quantity, wl_max: u.Quantity,
                      latitude: u.Quantity = 39 * u.degree, water_vapor: u.Quantity = 0 * u.um, n_layers: int = 2,
                      zenith_angle: u.Quantity = 0 * u.degree, resolution: int = 0):
@@ -154,7 +156,7 @@ class Atmosphere(AOpticalComponent):
 
         Returns
         -------
-        data : str
+        data : QTable
             The ATRAN computation results
         """
         # Select closest latitude from ATRAN options
@@ -200,7 +202,7 @@ class Atmosphere(AOpticalComponent):
         # Check if result is empty
         if data == "":
             logger.error("Error: Request returned empty response.")
-        return data
+        return self.__parse_ATRAN(data)
 
     @staticmethod
     def __parse_ATRAN(table: str):
diff --git a/esbo_etc/lib/cache.py b/esbo_etc/lib/cache.py
new file mode 100644
index 0000000..4cad241
--- /dev/null
+++ b/esbo_etc/lib/cache.py
@@ -0,0 +1,4 @@
+import percache
+
+cache = percache.Cache("cache")
+cache.clear(3600 * 24)
diff --git a/requirements.txt b/requirements.txt
index d67becd..c87df02 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,4 +8,5 @@ pyfiglet~=0.8.post1
 
 Sphinx~=3.1.2
 sphinx-rtd-theme~=0.5.0
-requests~=2.24.0
\ No newline at end of file
+requests~=2.24.0
+percache~=0.4.4
\ No newline at end of file